mouse and keyboard drivers keep disappearing.

Hi,

A friend has been having trouble with a powerbook that is using a kensigton mouse and keyboard. He has some apps that were spontaneously crashing. I suggested he run onyx and do some cache cleaning and permission stuff. After wards the mouse and keyboard stopped working.

But they were working in the spare testing account. Then they stopped working in that too. He downloaded the latest drivers and installed them and everything was working fine untill a reboot, then they stopped working again.

Does anyone have any ideas what might be causeing the mouse and keyboard to need to have the drivers reinstalled to get them working again after a reboot?

Thanks.