Jack I've never changed the USB since I've had this system, and it's always worked. We had a power failure several weeks ago,and that's when the issue began. I feel strongly that some setting in the BIOS has changed, but I can't get to the BIOS setup screen until I get a wired keyboard to be sure. Once windows has booted the keyboard is fine. If I could get to the BIOS screen directly from Windows 7, I would be able to see/change the settings, but as far as I know, that's not possible. The BIOS is only available during the first few seconds of powering on the system (by pressing certain keys, which I can't do at that time), but not once Windows has started.