Keyboard & mouse quit on laptop

I hope I'm posting this in the correct forum. I'm working on a friend's laptop: a HP Pavillion ZV6000, running Win XP Home SP2. Neither the onboard keyboard or the mouse are working. I've reinstalled the OS & drivers, & they both worked for a time, & then quit again. Again, I'm not sure if this is hardware or software related, so wasn't sure where to post. I took the keyboard cover off & all seems to be connected ok. I have updated all the drivers, etc... No spyware seems to be present, as none is detected in AVG, Ad-Aware, or Spybot. Does anyone know if this is a hardware issue, & if so, where to start with troubleshooting? It seems that laptops are made so that a person almost cannot get inside them, so if I take it apart, it would be great to know what to look for. In device manager, under "Mice" there are 2 devices listed & I'm assuming one is the mouse I have connected using a USB port, which works: "Microsoft USB Intellimouse" -- which seems fine & "PS/2 Compatible Mouse" which has a yellow exclamation point by it; however, no luck with updating drivers, etc... Any ideas? Thanks in advance!
shanrene

 

Is there a button to turn the trackpad on and off?
And does the keyboard show up in Device Manager?