dead usb ports

i have a INTEVA pc with a usb problem. i have checked all the normal culprits to no avail.It powers up device on startup but then drops it upon completion.Im running win98 o.s.In device manager it labels the device as unknown with no drivers installed,even though i have run manufacturers install software.Someone please suggest a program or advice on how to diagnose this problem.THANKS IN ADVANCE rg