I am a University Student worker trying to find a quick fix to a keyboard and mouse problem we've been having on our dells.  The model is Optiplex GX260.  On boot up the keyboard and mouse are recognized by the comptuer.  I can get into the bios and i see the light come on the optical mouse.   I can enter the bios and make any necessary changes there.  However, once I exit the bios and the first windows boot up screen appears the mouse light turns off and the keyboard ceases to function.  At the login screen, I am given no indication that my mouse has been recognized.  Sometimes this problem fixes itself by restarting the machine.  However I still have a couple machines that refuse to work even after 5 reboots.  Currently I have PS/2 Mouse and Keyboards hooked up to these computers as a temporay fix.  One last thing, I know these keyboards have worked on these computers before.  Anyone else experiencing a similar problem or know an easy fix?  Any help would be greatly appreciated! Thanks.