I have a 8320 Curve which i purchased on ebay last spring. I have had no serious issues with the phone until this weekend when it stopped playing the notification tones. Luckily I have my sound profiles setup so that it also vibrates. My daily alarm has the same problem, it only vibrates. The speakerphone also doesn't work. Here is the weird part, I can still hear the music played through the media player on the phone's speakers! I have tried pulling the battery but that did not work.
Mine was doing that the other day, it happened after I synced everything from my wifes curve to mine. On tone that worked were the generic ones. All my downloaded ones would not play. I deleted them and redownloaded them.