GA-MA790XT-UD4P going bad?

Well I think this GA-MA790XT-UD4P may be going bad. it will load windows xp or 7 half way then reboot. Tried changing video cards, memory, memory slots unplugging everything ect. The one thing i did see is in xp safe mode the usb mouse did not want to work and then a ps/2 was working. When I had the USB keyboard plugged in the mouse would not work ever.

So the last thing I can think of is changing the cmos battery but it holds the date and time fine.

ideas plz.

ermm checked for shorts?

not sure where to look but ill just break the whole thing down.