I was using my TrackIR 4 with the TrackIR software 5.0. Today I upgraded to TrackIR 5.1 b3 and since that, the TrackIR suite is not usable any more. Every time I start the software, the initial screen appears and after a few seconds (without showing the current "camera view" on the right side) the MS Windows error dialog ("TrackIR 5.0 has encountered a problem..." / On a german WinXP "TrackIR 5.1 hat ein Problem festgestellt und muss beendet werden.") shows up and after that, the software is shut down.
Then I tried to remove TrackIR 5.1 b3 and to reinstall TrackIR 5.0 again, but now the same error shows up, too. No matter what I do, the TrackIR software crashes all the time.
Latest version of TrackIR 4 seems to run fine; anyway, TrackIR 5.0 ran fine before too

Any suggestions how to solve this?
My system runs on Windows XP SP3, TrackIR 4 and TrackIR 5.0. Graphics card is a nVidia GTX260 (till today)
Thanks a lot!