[Dubdub]

The problem typically has 2 causes - lint under the track ball or it got wet.

The best fix for dirt or lint that I know of and to amplify what Ira said above: turn the device off. Press and hold the trackball and slowly rotate in the direction that it DOESN'T work. Then, continuing to press, roll it in every direction for at least a minute. Turn the device back on and see if it now works.

If that fixes the problem, great. And always keep it in a pouch, not in your pocket or purse as the case may be.

If it got wet, then all bets are off on your ability to fix it. As said above you could try to replace the trackball or have a repair center do it for you. There are several Youtube videos that show you how. And I think we even have something in our FAQ about it.