I have two Logitech mice connected to USB ports on my PC. When I move a
mouse, the cursor stalls or "balks" - then keeps moving. This happens very
frequently. Any ideas what's causing this to happen?
Might depend on the mouse technology.
If it's a balled mouse, might need cleaning.
If optical, might need cleaning or more likely it's on a poor surface.
Since it seems (because you didn't differentiate between the two mice)
that both have this balk, it's not so likely to be dirt.
If wireless, receiver might be too far away or too near metal objects.
An IDE drive or cable problem can also cause similar behavior.
Overclocking could cause USB port problems but generally the whole device
fails, not just a problem with smooth motion but still continues working.
Regardless if overclocked return to spec'd speed 'till problem is
resolved.
If you have a PS2 mouse or adapter for those mice you might try it. Any
other USB devices having problems? Can we assume that if you leave one
unlugged then the other still exhibits this problem?