Ever since I took possession of my ThinkPad T60p, it has suffered from an infuriating fault. When I am typing, occasionally, and without warning, the cursor will jump to somewhere else in the document. Sometimes it will even jump somewhere else and highlight a chunk of text at the same time. This means I can be typing quickly and inadvertently delete a sentence from three paragraphs earlier in the document.
It drives me insane.
I figured out the problem today. My trackpoint (the red nipple) was configured to support "Press-to-Select".
I must have been brushing past it as I typed and making it think I had clicked the mouse. So, the insert cursor was jumping to wherever the mouse was positioned - and highlighting a section if it sensed that I was pressing for a longer period of time as I brushed over it.
The solution was simple
Control Panel -> Mouse -> Ultra-Nav Tab -> TrackPoint Settings -> Deselect "Enable Press-to-Select"