I noticed that this is posted already for the HTC tattoo, but both my wife and I are having the same issue on our Verizon (USA) Incredibles, so I thought I'd post here. The problem seems to happen more often since the 2.2 update. Custom ringtones for individuals, as well as default ringtone, change for no reason, as do notifications. I typically set my notification at zero volume plus vibrate, then the next day I'll hear a notification go off, and find in the settings that the checkbox for using the same volume for notifications as ringtones is checked again. So I have to uncheck it, and slide the notification volume back to zero. Is there some way to lock my settings?