I am working on the same problem on a Toshiba A300 laptop and I was given this as a fix... I am going to put it in as soon as I make the changes in Vista from French to English, so I have more things to do before I get to the point of deleting a file...
http://smokeys.wordpress.com/2008/05/31/windows-vista-usb-device-detection-problems-how-to-fix/ I hope this helps