Are your USB keyboaard and mouse plugged into USB ports or do they use little adaptors and plug into the ps/2 ports? I had a similar problem with SUSE 9.2. When I had a USB keyboard plugged into the USB port my system wouldn't boot since I got the "no keyboard" error during the POST (Power On Self Test) sequence of the BIOS. I found a small adaptor at Maplin Electronics which did the trick. The part is a "USB Adaptor AF/Mini Din 6pin M" the part number/order code to use at Maplin is A78AH. All you do is plug your USB keyboard into the adaptor, then plug the adaptor into the ps/2 keyboard socket and your USB keyboard should now work as normal bu through the ps/2 socket. My shiny new SUSE 9.3 system has no problem with this sort of setup. I have a Zippy Electroluminescent USB keyboard (again from Maplin) and a micro$oft USB trackball explorer thing for a mouse. They both use these adaptors.
Check the Maplin website http://www.maplin.co.uk
and do a search on the order code. They are £4.99 each.
There may also be an option in your BIOS to detect and use a USB keyboard. If there is it may not be enabled by default and you could try changing the BIOS settings for the keyboard. This may not work though.