mouse stops working in Windows 98

I have a computer with W98SE and a logitech wheel mouse. Started with the mouse in the PS2 port. If the power went out or the computer sat for a few days the mouse would appear to lose its drivers and not work. Upon reboot would have to reinstallthe mouse drivers from the disk. Changed to a USB mouse, Logitech wheel, loaded the drivers, works for a while, then mouse gets jerky and stops working. Again, have to reload the drivers to get it to work again. Any suggestions of what could be wrong?