Actually i had a similar problem today wth the 7100 build, dont know what was the real problem. Anyway i had installed bitdefender 2009 and did a restart after install and my mouse (microsoft sidewinder) was just dead, tried rebooting again but same problem. I decided to try just to put it into another usb-port and that did the trick for me. Dunno if it was related to the a/v install or something else but it was pretty wierd.