Rooted Droid 2 with Froyo 2.2 and 2.3.2 system update. Normally, my Twitter app is set to play the sound of a tweeting robin when I receive tweets. Today, I put my Droid 2 into vibrate only mode so I could watch YouTube videos and listen to music uninterrupted. After turning the ringer volume back up, my phone continued to only vibrate upon receipt of new tweets. I finally opened Twitter and found that somehow, the tweeting bird sound had been unassigned as the alert! I manually reassigned it and all is well now. My question is simply, how did it unassign itself? Is this a bug in the Twitter app, or in Froyo?