I've tried looking online for anyone sharing a similar problem, but haven't had much luck (maybe I could've looked harder).
I've occassionally had the problem where I had Windows remove a USB drive (both 2.0 and 3.0) and:
1) There wouldn't be a confirmation balloon,
2) The drive still shows in the Computer window but isn't accessible nor does it show storage information.
To my layman's brain, it looks like the drive hadn't been ejected properly and now exists as a phantom on the system. This usually proceeds with Windows being unable to do a proper restart or shut down (even after waiting for over 5 minutes) and I'd have to do a hard shut down.
I feel like this is a bug on Win 7 cause I don't recall ever seeing this happen on other platforms. Also, I've seen this problem occur in some of the computers at my college computer lab (after they switched from XP to 7). Just thought of throwing this out there and seeing if I'm missing something.
I can't speak for the computers at college, but my specs (if of any help) are as such:
Win 7 Pro x64
Asus X79 Mobo
Corsair 4x4GB DDR3
EVGA GeForce GT 640
Samsung SSD 830
Hope someone has an explanation for this! It's kinda worrisome having to perform a hard shut down every so often.