In both cases check the connection:
Fault One: If you are lucky it is located on the power board. otherwise it will be on the MOBO. Also have you tried a USB mouse?http://cgi.ebay.com/HP-DV6000-POWER-BOARD-includes-cable-/260598216923?cmd=ViewItem&pt=Laptops_Nov05&hash=item3cacdd38db
Fault Two: If it is not the connection, and you are sure the mouse pad are working, it might be another MOBO issue.