I wonder if anybody has had experience with, or understands, what is happening with my computer system. I have an i7 Intel 930 CPU with 6Gb DDR3 RAM, a pair of nVidia GTX 460 1Gb video cards in SLI configuration, running Windows 7 64-bits. When I have one or more USB2 thumb drives plugged into the front USB ports on my computer everything works fine, and I can copy from and write to the thumb drives.
If I shut down and then reboot while one or both of the thumb drives are still connected Windows opens with a very low resolution on the display, and I get a message to the effect that a problem has been found with the nVidia cards and they have been shut down by Windows. If I remove the thumbdrives and reboot, everything works fine.
I upgraded to the most recent nVidia driver for my cards but that didn't solve the problem. My hunch is that it is either a conflict between the video drivers and the usb drivers for the thumb drive, or it has to do with the length of time it takes Windows to assign drive letters to the thumb drives. I have 4 internal HDD's and a CD/DVD drive as well as a multi-card reader that grabs several drive letters as well.
Since I discovered the trigger of the problem being the thumb drives at boot up, I can easily avoid it. However, there should be some way to solve the problem rather than use this workaround.