USB won't recognize anything

I plugged in a cheap usb optical mouse to my tablet pc and it acted strange
and then my laptop shut down by itself. after re-booting and throwing away
the piece of crap mouse, my usb ports don't work anymore. I have uninstalled
and installed all the usb and HID devices and drivers, restored my computer
to an earlier date, tried booting in safe mode, and re-installed the
operating sytem from the original disks. Also made sure all OS updates were
up to date!. The ports supply power, as evidenced by my Ipod charging, but no
recognition of the Ipod, camera, flash drive etc.
Anyone have any idea what I should try next, prior to sending my laptop off
for service, which i loath to do???
thanks