So if you wait long enough, it accepts input again?
Weird.
I dunno man, I'd probably have to dink with it to figure it out.
What do your resources look like? Is your processor gagging on something, maybe a virus scanner or other scheduled task? How much RAM do you have?
I was seeing weird lock-up issues lately, where the system would appear to hang, but the processor was just being monopolized by SVCHost.exe. It turned out to be a problem with Microsoft Update.
So try turning off Microsoft update???
Just taking stabs in the dark.