Not sure I am alone on this. I found that the mouse cursor internmittenly drifts to the top left corner of the screens. This happens while I am using the track pad and also when I am using an external mouse.
I read something about cleaning the trackpad, which I have done but did not fix the issue
Is it consistently happening (i.e. you know it’ll happen again after x seconds)? Does it resume consistently after a restart? Can you get a sense of whether moving the laptop affects it, e.g. does holding it on the right side and twisting your arm to rotate it trigger it? (Careful! )
It sounds like the TrackPoint on your IBM ThinkPad is suffering from the usual pressure overload issue.
Does the problem happen with no mouse connected? If there is always an optical mouse connected, I would look very carefully in the lens area. I’ve had very fine fibres there before that wave around in the tiniest of air currents and the sensor was picking it up as movement.