There are several of these seemingly related threads now active on the forum, dealing with occasional unpredictable random "freezes". I myself am thoroughly
involved in this thread and have been chasing a similar problem for three months now, on three different machines.
All machines run Win7. All machines have NVidia GTX 1050ti graphics cards and run with the latest NVidia GeForce driver. All machines have wireless USB Logitech mice (Performance MX, and MX Revolution) with a USB receiver. All machines have an external USB 2TB drive (i.e. SATA drive in a USB 3.0 enclosure) used for backups (nightly scheduled to run automatically from both Macrium Reflect and NovaBACKUP). The external USB 3.0 drive is from Verbatim, and is "managed" by their Green Button software (which spins down the drive if it's not been accessed for 10 minutes).
Both desktop machines have two Eizo monitors, running "extended desktop". One setup is a pair of 24" Eizo S2433W monitors running 1920x1200, with no USB cables connected. The other setup is a 24" Eizo HD2441W and a 31" Eizo CG318-4K, both of which have USB cables connected to the PC (to support the USB connectors in both monitors).
Two machines are home-built based on ASUS motherboards (P8Z77-V Pro with Intel i5-i3350p CPU and 24GB RAM, and Z170-Deluxe with Intel I7-6700 CPU and 32GB RAM), with the older P8Z77 machine having just died (due to repeated hard power-off/on cycles caused by repeated freezes). The now dead machine was just replaced by a brand new Lenovo M910t machine, which is also freezing.
All machines have TV tuner cards in them (both Ceton InfiniTV 4-tuner and 6-tuner, as well as Hauppauge OTA/ATSC 2-tuner and 4-tuner) and run Windows Media Center through external Linksys DMA2100 extenders around the house all connected via ethernet cable to the LAN (managed by a Netgear R7800 Nighthawk router). Ceton cards are cablecard-enabled, and also talk to a Motorola Tuning Adapter (for SDV) through USB cable interface.
Six Netgear switches around the house (three GS105 and three GS108) to support "nodes" of Internet-aware devices. Two Netgear routers (WNDR4000 and WNDR4300v2) connected to a nearby switch and running in "access point mode" so as to provide WiFi network coverage all round the house, far away from the primary R7800 router which cannot reach all locations.
I had originally been suspicious of USB issues being at the heart of my problems. I thought it was a failing USB interface on the Z170 motherboard, and initially bought a replacement identical motherboard. I have procrastinated about performing the time-consuming "surgery" needed to replace an already installed motherboard in this machine, but it was my plan.
And then my other P8Z77 machine also was freezing, and eventually died. I decided to focus on getting it back to life with a new M910t, transferring the WMC duties from the Z170 to the new presumably 100% dependable M910t. Turns out this was false hope, and the brand new M910t freezes too. So it's obviously something else in common with all of my machines and LAN and environment and setup.
I then just this week discovered it seemed to be tied to the fact that I was running with "screen saver (Mystify)" active after 6 minutes, along with "turn off display after 10 minutes of inactivity" to put the monitors into hardware power-save mode during long periods of inactivity. That, coupled with flipping the power on/off button on my Logitech wireless mouse when not in use for a long period so that I would have to slip the on/off button again and jiggle the mouse to bring everything back on the screen back to life when I return... that seemed to be very much tied to the "freeze" happening.
So for the past few days I have been operating with some tweaks:
(1) I've turned off screen saver,
(2) I've set "turn off display" to NEVER,
(3) I've left my mouse on/off button in the ON position even when not used for long periods,
(4) I disconnected one USB cable to one Eizo monitor (where the USB Logitech receiver was plugged into one of its USB ports) and moved the receiver to a USB port in the other Eizo monitor (which was still connected via USB cable).
Unfortunately, although my two machines now ran 1 day and 2 days without a freeze, just this afternoon it happened again... and affected BOTH machines (as was often the case, one of the mysterious clues)!
Turns out I had taken to manually powering off all monitors (with their on/off buttons, instead of my previous approach of using screen saver and then power-save mode initiated from PC) and also casually powering off the Logitech mice when placing them on their re-chargers (thinking it really was the screen saver tweak which was causing things to seemingly stabilize finally).
Well, this afternoon something went awry again. One symptom I'd observed previously was that it was only the external screen/mouse/keyboard which appeared frozen. If I went to the other non-frozen PC and checked with Windows Explorer sure enough I could still get to the mapped network drives on the "frozen" machine and run apps on the non-frozen machine that accessed data/folders on partitions of the "frozen" machine. So Windows wasn't really "frozen"... it was the screen/mouse/keyboard that was all somehow UBS-related and influenced and that appeared to have locked up.
This afternoon, when I powered on the monitor I saw that the clock showed the proper current time of 1:38PM Jan 28, and I thought everything was running. When I then powered the mouse back on, that's when things instantly froze. So the clock (and by inference, Windows as well) was seemingly running normally right up to 1:38PM... until it froze when I jiggled the mouse that I'd just powered back on.
Before doing anything more I then went downstairs to check the other PC which also had both of its monitors powered off and its mouse powered off, and lo and behold when I powered the monitor and mouse back on well it was frozen as well!! Unfortunately I had nothing on the screen to see, which was just black, with no residual output showing the clock. So I don't know when it actually froze.
But when I returned upstairs and got that machine working again I noticed that my regular nightly Macrium Reflect backup (which normally runs at 4:45AM) kicked off, as it will do if it senses that its previous scheduled backup was missed and if I don't cancel this "catch up" run. Double-checking its log, I confirmed that the 4:45AM backup had indeed not been performed, implying the machine had been frozen at 4:45AM which was long before 1:38PM this afternoon when I powered up monitor and mouse and first noticed the freeze.
A short time later I noticed that my normal nightly NovaBACKUP job also popped up its completion message, implying that it too had just run a "catch up" backup from its own last missed scheduled run, which is at 1:30AM. Well that means the "freeze" had actually been in effect all the way back at 1:30AM last night, again having nothing to do with my power on of the monitor and mouse at 1:38PM this afternoon.
So, I was actually working at this "frozen" machine sometime earlier last night, and eventually packed things up and powered off monitors and mouse and went to bed. I can't recall exactly when this was, but it certainly was prior to 1:30AM when the NovaBACKUP was scheduled to run but didn't.
Now I suppose it's possible that the spun-down (by Green Button software) external USB 3.0 Verbatim drive somehow missed its signal to power-up (which would have occurred when NovaBACKUP should have kicked off at 1:30AM), perhaps because of a flaky USB interface on my motherboard. Or maybe the USB enclosure dropped the signal. Or maybe the SATA drive inside the USB enclosure just failed to spin up. Who knows? But it again does seem USB-related, same as I have always felt was relevant.
Bottom line: I still don't have an absolute answer or solution to my own similar problem, which somehow seemed to have started about 3 months ago... after uncounted years of 100% reliable 24/7 performance for all of my computers, all of which had been running the very same hardware and software setup forever (including screen saver, power-save, etc.) as well as my own habit of manually powering off things when I was going to be away for an extended period and then manually powering things back on and jiggling the mouse to wake everything up.
I'm suspicious of an NVidia graphics driver update which is involved with screen saver and power-save mode for monitors, which underwent a major version change in mid-December in support of a new family of RTX graphics cards NVidia now sold.
I'm suspicious of the Intel and ASUS and Lenovo (and every other manufacturer) firmware/BIOS changes made last year for the Sceptre/Meltdown CVE vulnerability along with the associated Windows Updates made by Microsoft to support the hardware changes.
I'm suspicious of Logitech wireless USB mice/receivers, although I don't recall upgrading the installed Setpoint software/driver in quite a while (but I might have).
I'm now suspicious of my external Verbatim USB 3.0 backup drives perhaps going flaky, because of its clear connection to my 1:30AM NovaBACKUP job not running last night as scheduled. So either failing to come up from spin-down was the "trigger" event for the current freeze, or perhaps things were frozen earlier for some other reason so that the spin-up command never even went out over the USB connection... don't really know.
I have two USB wired Lenovo mice I can try, instead of the two wireless USB mice currently being used. Still USB, but at least not Logitech and not involving a USB receiver.
I can remove the one remaining USB cable I still have connected to one Eizo monitor for use by the Logitech receiver I moved over to this monitor (when disconnecting the USB cable in the other monitor), just because using a wired mouse on this machine presents a minor cable length problem to be dealt with.
I have previously experimented with disconnecting one machine from the Internet (by pulling its ethernet cable out), allowing it to be focused strictly on running as a WMC HTPC doing recordings which I could watch on the connected monitor. Without an ethernet cable to the LAN I couldn't watch TV through extenders throughout the house, but I still could watch on that HTPC monitor. My objective was to determine if somehow there was a LAN-based cause for this freeze symptom. Of course this afternoon's clues would seem to confirm that there is some kind of "sympathetic" effect where a freeze on one machine can seemingly result in a freeze on the other machine, as obviously happened just last night to me... at 1:30AM for sure or possible even earlier on one machine, clearly impacting both machines by 1:38PM this afternoon.
So, I can't help you yet. And your situation may be completely different from mine which appear to be very much USB-related, and may actually be due to some genuine hardware/software/setup issues unique to you.
But I assure you that you're not alone. MANY OTHERS are complaining of this mysterious "freeze" symptom, all around the place.
