Hi Keef, Let us try uninstalling the USB Root Hubs in Safe mode: If you are able to boot the computer in Safe mode, please check and let me know for how long do the keyboard and mouse work in Safe mode.
I have run into a problem in which my keyboards, especially the newer kind such as the KB212-B, and mice will not run after windows has stated that they are "ready to use". Upon logging in they work fine, it will then search for a driver, and once that is completed they will cease to function and the computer will freeze. I turn off the computer at this point, and plug the devices into new USB slots, but the same thing occurs, over and over again. Any help would be greatly appreciated. Keef
Dell Keyboards/Mice don't function correctly on Vista