I have been suffering from a most infuriating problem for the last few months. Every now and again when I'm typing my cursor will jump to the beginning of the line. Since I don't touch type I spend quite a lot of time looking at my clumsy fingers and not at the screen so when this cursor jumping happens and I don't notice it can cause carnage to my document. At other times it was causing a seemingly random word to be selected and as I continued to type would overwrite it. As you can imagine this weird behaviour started messing with my head.
Having worked in IT Support in a previous life I am well aware of the need to find a reproducible set of circumstances in order to trouble shoot a problem. Since I spend most of my life in my beloved Lotus Notes client that was where I first spotted the problem. My initial thought was that it could be a bug in the editor since there had been loads of improvements to it in recent releases (drag and drop stuff mainly). However, it didn't take long to spot the problem happening in other applications including Firefox and even Notepad. With my support head on I might have suspected "Finger Trouble" but even though my typing is not great it isn't that bad.
However, I just had a stoke of luck. For no particularly good reason whilst in an web based editor I just happened to tap my Trackpoint and witnessed my cursor moving to the beginning of the previous line! But that is dumb - since when have trackpoints behaved like mouse buttons? Well after a bit of research I found out that this behaviour is called "Press-to-Select" and can be configured in the Control Panel/Mouse. I have been using Thinkpads for 13 years and I am sure that it has never been turned on in any of my previous machines - I wonder why the default has changed to on now. Whatever, at least I understand what is happening so now I need to decide whether to turn it off or to take advantage if it.
From the Trackpoint tab in the Mouse menu you can configure your trackpoint.
Ticking enable Press-to-Select allows you to configure that particular function.