Mine did that as well this past week. Intermittently; if I reboot, it will do it for a time or two, then quit again.
Then all of a sudden it seemed to get better. I don't know if it was something that got pushed onto the phone that goofed it up or what, but it happened all of a sudden-like.
Don't really have any advice except battery pull. Maybe someone else can weigh in?
I have the Blackberry Pearl and recently "updated" my phone.... What a HUGE mistake! My ringtones have been completely disabled! I can't use the preloaded or the ones I've downloaded.... Can someone please tell me what to do???