windows restart problem

hi
not sure if this belongs in the hardware or software forum.

a friends computer has a weird windows problem. if you shut down, and then turn on - everything is fine. But if you do a "restart" the mouse and keyboard freeze up at the windows user logon screen. It is a older model p3 600 running xp home. I believe the mobo is a tyan s1854 trinity 400

what do you think? maybe cmos battery?

 

Could be CMOS battery. I've seen some WEIRD problems arise from a dead battery; things you would never expect. For the $5 to replace it, it's probably worth a try. They are typically rated for about 5 years lifespan.