could be that the mouse is on its last legs (no pun intended).
Or it could also be that the virus is still present in your system; if this is the case, I would suggest you follow Grif's(M) advice in this other post (different O/S, but works with all O/S's) http://forums.cnet.com/5208-7813_102-0.html?messageID=3313305&tag=contentMain;contentBody#3313305
I have a Toshiba satellite a205. I had installed win7 and all was alright until I got a suspected a virus. I re-installed and now every second boot starts with a frozen mouse. I re-installed the mouse drivers but it didn't help. Whats a guy to do ?