I have an HTC Touch 3G. This is my first smartphone and I love it. However, there is one problem that I have been having with it. Sometimes (notably when increasing the volume from "Silent" or "Vibrate" mode), a system database file gets corrupted which has the following effect: the volume and vibrators work perfectly, except in the case of a new incoming text message. When a new text message arrives, the phone vibrates, but there is no alert sound to be heard. Some googling took me here, which had a solution. That solution did not work for me, but it did help me arrive at this solution.