Win7 crash

Quite old win7 machine, well, ancient really. It's behaved perfectly for years but I'm experiencing a complete lock up prob.
After a few hours the machine just locks up and mouse, keyboard unresponsive. A quick reset on the power button and all systems fine until the next crash.
Pls. note the following ...... Eset security all clear, malwarebytes all clear, all temperatures in the low 30s, no new progs installed and have more than adequate memory available. sfc all clear and chkdsk all clear.



If I was graced with a BSOD it would really help matters but no such luck and ctrl/alt/delete impossible to perform.



I use Express VPN which I suspected but the crashes occur with it switched off.


Any ideas most welcomed folks.

I agree with SIW2. A repair install could save a lot time spent on trying to find out the issue.
Before you do it, do some basic tasks.
- Clean your disk (%windir%\system32\cleanmgr.exe) or use CCleaner
- You must have at least 20G of free space on C: drive.
- Do a check disk. Open a CMD window as administrator and type
chkdsk C: /f
It will say your disk is in use and if you want to schedule to next start = Yes
Reboot
Pay attention on the results, specially bad blocks, bad clusters, bad sectors that are indication of physical damaged disk.

Thank you all so very much for your replies.

Repair/install seems the way to go (eventually) but I do have a Macrium copy on a spare HD but it's about 6 months out of date and I was going to update it and then the problem started so I reasoned that if there was a software prob then the new Macrium copy I would make would carry on the chaos.
jftr, would a faulty mouse or keyboard cause my probs? I watched my 'puter today, awaiting the inevitable crash, and seconds before the crash the mouse became extremely 'jerky' and jumping around the screen instead of moving smoothly. System check later showed the mouse was fine so could be an intermittent fault but I've plugged the mouse into another usb port and no crashes in the last 4 hours.
Once again, thank you all for replies to date and I'll post progress later especially if the mouse/usb port is the problem.

About 10 hours and no crash so it would appear that there is a dodgy usb port but it doesn't show as dodgy in System devices (USB). Might invest in a powered 4 way usb splitter just in case. jftr I googled faulty usb ports and it was confirmed that semi-duff ports will crash the 'puter. I consider that a BSOD message would have spotted the prob much earlier. We live and learn!!


Thanks again to all.

I swopped the mouse and keyboard usb inputs on the 'puter and all seems fine.