Help With HP Synaptic Touchpad Issue

Can anyone advise me on how to fix my HP ze4315us laptop Synaptics touchpad that no longer functions? My laptop only recognizes a USB mouse that I occasionally use. A little background:

It worked fine for awhile. Occassionally, I use a corded USB mouse. I used to be able to just plug the mouse in, boot up and the laptop recognizes the mouse and disables the touchpad. When I unplugged the mouse, the touchpad would work (after rebooting). For some reason, now the touchpad does not work at any time.

I tried:
1. Updating the Synaptic touchpad drivers - no dice.
2. Going back to previous system settings when everything was working. No good.
3. Uninstalling the mouse via Settings/Control Panel - nothing.

Intermittently, the touchpad works while XP Home is loading, but after XP fully loads, the touchpad stops working.

Any ideas?