I have a similar problem, using ms optical usb mouse, winxp pro, abit ic7-max3 mobo, p4 3.2G, 2G matched DDR ram, ATI 9800XT video card, twin 120g SATA HDD, running striped raid.

System has worked great for months, lately the mouse 'stalls' (no buttons work either), the light goes out, the only way to get it going again is to pull the plug out and put it back again.

In my investigations so far, it is NOT: a system standby/hibernations issue, USB hub power issue, and yes i have tried serveral different mice.

Possibly a virus? dunno have norton running and it hasn't picked anything up.

There doesnt appear to be background software running that is causing it either, the problem occurs at different times, more or less often.

I am currently at a total loss.