Have you tried plugging them in to your other USB ports? If not, I would try that since USB ports can go bad. I have had USB problems with an older PC where it either wouldn't recognize what was plugged in or it gave me intermittent connectivity issues. You could also try your mice on someone else's PC to see if they work or not. I had an external hard drive that started causing connectivity issues until one day it was no longer recognized at all. I even called Maxtor support but they couldn't help. I bought a new power supply, that didn't help. I plugged it into two of my newer laptops and lo and behold, it worked with no problems whatsoever. I also had intermittent problems with both MS and Logitech mice & keyboards that were connected to the older PC, but those mice and keyboards worked perfectly fine on my newer PCs. That's not to say that a newer PC can't have a bad USB connection, though. Other than my older PC, I have not run into any issues with the same mice or keyboards on any other PC (two laptops and another desktop). Well, wait...actually I did have some issue with a Microsoft wireless keyboard & mouse. The wireless station was something that looked like another mouse that was plugged in via USB. The thing literally had to be right next to the mouse & keyboard, or else it gave me problems.