Ok, most of us know about this problem but I've not heard of any solution and I am becoming convinced that it is a software issue and not just a hardware/design flaw....
If one were to hold on the trackpoint, pushing it in one direction or another for too long, the computer starts to take control over the pointer and it fights against the direction you want to go. If you let go at this point entirely, the mouse cursor moves all on it's own.
A work-around so far, is to occasionally let go of the trackpoint during use, and if you do this often enough, the problem just doesn't happen in the first place. But sometimes it's easy to forget this, and when that happens, it's an annoyance to an otherwise awesome design that overall just works...
I want to work with the community on fixing this if we can, or getting help from the developers/drivers if need be.
One thing, I have noticed, is that if you get the problem to occur (or purposely strive to re-produce the issue) the only way to get it to stop is to wait several seconds until the cursor completely stops moving. If you try to fight against the cursor, or move in any direction, you just end up delaying the amount of time it takes for the issue to go away, so it's best to just sit and wait it out for a second while this is happening. You could literally keep interrupting/fighting against it, and it will continue on in error until you give up. Because of this, I suspect that an adjustment in software or drivers might make it possible to completely correct this nagging and long standing issue that if I am not mistaken, spans multiple Lenovo systems (not just the X220), but I could be wrong on this, I only have this machine to test....
When I first looked up this problem a while back, one poster mentioned that it's part of the design of the stick, counterbalancing itself, but since if even you help it and push it in the direction it wants to go, it still continues in error until you simply wait a period of time. And with that observation I'm questioning if there isn't more to it than just hardware counterbalancing in the joystick, but rather an issue with the ways in which the driver interacts with the hardware under these very specific circumstances.
I really would love to see this issue fixed. It's been here since I bought the laptop on day 1 and exists both on the factory Windows 7 install that I still have on this machine and as well on my Windows 8 install. On the Windows 7 side I am using Ultranav drivers and on the Windows 8 side I am using generic Synaptic drivers and the problem is identical.
If you are trying to reproduce the problem yourself, one strategy is to push the pointing stick very gently, but consistently in one direction without letting up, consistently keeping the same pressure until you see the cursor stop itself/fight against your input, and then let go and watch it move on it's own in the opposite direction. You might have to try this several times until you get the right pressure but soon enough, if your system is like mine, you will spot the issue and find it fairly easy to reproduce if you try.
If anyone else has been experiencing the same behavior (occasionally or frequently) it would be useful if you could just post that you run into this issue also, just so that it can be clearly defined as a widespread issue that would appreciate some attention. Of coarse any additional observations concerning this phenomena would be extremely welcomed.
Thank you very much, hope to get this one fixed. TrackPoint / pointing stick is hands down my favorite built in laptop mouse style, and with practice I have learned to simply avoid this unfortunate behavior more often than not, but it still pops up despite my best efforts and it's rather frustrating as I am sure you either already know or could imagine. -cheers