USB thumb drive delays in mounting.

After the computer is freshly booted, the 1st time I mount a USB thumb drive it will take 20 seconds to appear in the "Computer" window. It will instantly appear in the device manager along with the audio tone that signals it has been connected; but I still have to wait 20 seconds before I can see or access it. Thereafter, connecting any USB device will mount without delay until the computer is re-started. The delay only happens the first time I insert a USB drive after starting the computer. This started last October. I tried SFC, virus scans, a 'clean-boot' and none of those helped . It's particularly annoying when I raise the lid of my USB scanner and have to wait 20 secs before I can scan something. I hope someone can point me in the right direction.

I've tried all USB slots, front and back and even one that is connected to the hub that is built into the monitor. I get the same result on all of the slots. Thanks.

Strange indeed!! The computer in question has two on-board usb3 ports and several usb2 ports. The problem exists on all of the ports whether or not usb2 or usb3. See my system specs for the mobo. It is one of the earlier mobos to include on board usb3 ports.
I have some additional information that might provide clues for those who understand this stuff (I don’t).
• As I mentioned earlier, the problem is seen both for thumb drives and my (Fujitsu) scanner. Normally once a usb device is mounted for the 1st time after boot-up further mounting for any usb device happens without delay. Occasionally, I see the delay even for a 2nd device being mounted but that’s rare.
• After a usb device is plugged in, during the delay period, the device manager shows the device in the General Tab with the status that “no drivers are loaded for this device”. After the delay when the device is mounted, the status changes to “This device is working properly.”
• I’ve tried a number of things to fix this problem. From within the device manager I uninstalled and reinstalled the scanner driver. It had the effect of solving the problem for a full 2 days and multiple boots before the problem returned. I thought it might have something to do with MSE being updated last October so I turned off the real time scanning and it fixed the problem. Then I turned it back on and it took a day or two for the problem to return!! I even replaced the scanner cable and that fixed it for about 12 hours. Trust me, I know how weird this sounds!
• I’m certain that the scanner never had this delay problem prior to last October. I’m not so certain about usb thumb drives but I don’t recall ever having to wait for them to mount prior to October.
• I have two other windows 7 computers (no scanner on those and usb2 only ports) and they also show this delay in the same way for usb thumb drives! On those computers the delay is a little shorter, like 10-15 secs instead of 20 seconds.
• The last two observations raise the question as to whether some windows update from the October timeframe is responsible for this problem. All three computers are fully up to date with windows update set to automatic.
Hopefully someone will have something to offer on this. I’m running out of ideas.

Try updating the USB controller drivers. I would also update the chipset from manufacturer.

If you rely on a scanner to send scans to PC from scanner glass then I would install the scanner's software necessary to keep communication open between the PC and scanner when Win7 starts, then keep it plugged in. This may in itself resolve your problem.

Thanks for looking at this gregrocker. In the device manager I searched for an updated driver for the USB controllers and anything else that was usb related. In all cases the best driver was already installed. I used the “Intel Driver Update Utility” to scan for a later chipset driver. This Intel Utility installs the latest version as determined to be needed. It returned with the current “version is valid.”
My thought is that some update that was done in the October timeframe is probably causing this issue. The reason for this thinking is that I have three Windows 7 computers all of which demonstrate the delayed USB mounting after boot-up. My windows 2000 computer does not have this problem. While only the computer in question has the scanner attached, the behavior is the same for any usb device again suggesting that something happened to all three Windows 7 computers in the October timeframe when the problem was 1st noted (such as a windows update maybe?).
I know this problem is more in the minor-annoyance category and I really don’t know how to rule out that some update is the root cause but I thought I’d check in with the forum to see if any other ideas make sense. Agree, disagree or comments anyone?
Also, is anyone else seeing delayed usb mounting right after a boot-up on windows 7? It’s easy to test this: Re-Boot the computer, open the “Computer” window and make sure “Devices with Removable Storage” is displayed. Then insert a USB thumb drive and time how long it takes from insertion until the thumb drive is displayed. If it takes 10-20 seconds then you are seeing what I see. The second time you do this following the boot-up it takes about 1 second to mount. Again, I see this on all three of my Windows 7 machines.

What I would do since it's not that urgent and more of a project, is work through the Troubleshooting Steps for Windows 7 to check your system over thoroughly and gather clues. If nothing turns up after all steps leading to a Repair Install or Reinstall then it's likely a hardware issue.