Thanks for the pointers - I played around a little bit with the pointercal files under etc. It is not solved, so far.

What is strange that the 2 left items are not callibrated (I have to click even further then the outest ring, just about where the horizontal line starts). The 2 right items (2 and 3) I can calibrate correctly

I also put in the pointercal numbers from this link. No change though..

The N810 was not put out in the rain, recently. I usually keep a close watch on the gadget. I use it a lot though.

This is my pointercal file: