the problem is the mouse pointer darts erratically around the screen, clicking on windows etc. randomly. it happens at random times- and sometimes the PC crashes completely- spec (on a 5yr old PC) is Windows 98SE (it also happened on 98), Logitech 3-button mouse (also happened on a Mitsumi mouse), Pentium III 450, QDI BX motherboard I've run Grisoft's antivirus and spybot- nothing found. is it just a case of knackered motherboard? or processor, even? time i got a new PC? thanks.