If the pointer is going to one corner, that usually means that there is something stuck between the bezel and the TS overlay. It also sounds like it could be a controller problem. I'd try to take it out of the case and then calibrate it. If that doesn't work, a new controller costs $40 or so.
If you want, you could try to contact the MP3car store and see if they'll do warranty service on it, it's only 3 months old.