Uninstalling drivers does not remove PS/2 support. There is another issue here. Even with no drivers, my LX700 Logitech setup will work fine. You need to try to start in safemode and then reinstall chipset drivers. USB keyboards, no matter the extra features, should work without installing drivers. Same goes for any PS/2 hardware. They do not require drivers to function. Make sure you have USB Keynoard/Mouse enabled in BIOS as well. There is a chance that could be the problem.
Intel E6300/Nouctua NH-9U w/dual 92mm Panaflos
XFX 680i LT
Patriot PC2-6400 2X2GB LL
2 X BFG 8800GTX in SLI
Enermax Revolution 620W PSU
ASUS 24X DVD/Seagate 250GB SATA 2/THermaltake A90/Windows 7 Ultimate 64