Sounds like a driver power state failure.
Turning on driver verifier may cause a bsod we can then read the minidump for and get some more direct answers. Anything right now would be pure guesswork.
Instructions for activating driver verifier follow
Driver Verifier - Enable and Disable
(Please read all instructions for driver verifier before using as it's possible it will make the machine behave badly and you need to know how to undo it.)