I had something strange happen with Vista a just few weeks ago. The computer went into sleep mode and then I had much difficulty getting it to come back. The problems I had went away once I got the computer out of sleep mode and turned off completely. The software turn-off feature was malfunctioning for some reason and kept putting the computer to sleep instead.

In the situation you describe, which sounds a little different, I'd usually try starting the computer without the peripheral attached, then start it again with it to try to get the plug-and-play feature to start over.