I downloaded an application named Todderlock so my children could just meddle around with my phone while they sat in my lap. However, the sound stops working after a non-specific amount of "dings" when either tapping the shapes around the screen, or when dragging your finger along the screen to make the same type of noise, but much more rapidly. Thinking this was an application problem, I had my wife download Todderlock on her HTC Hero, and the sound works without issue. So, I shrugged that off and went looking for other neat applications to download...I downloaded Bug Squash I, II and III and they all suffer from the same problem: after squishing X amount of bugs, the SFX stop (the music continues however), and I have to restart the application to enjoy the sound for as long as it lasts. I was getting suspicious, so I loaded up Robo Defense FREE and the same thing happens when the turrets are firing...after X amount of shots fired, all sound ceases to work. I have not been able to find a similar problem with the HTC Evo on Google or here on the Android forums, considering my wife's Hero works without issue on all the sound issues I am having. As far as I know, phone notifications and ringers continue to work after the application has "disabled" the sound. I have not reset the phone to factory settings or anything, but I have restarted the phone itself numerous times, and the problem still persists.