Sadly i had this happening like crazy the other day while mowing the lawn.... I realized though that i needed to put the phone on lock cause the heat from my leg was causing it to skip and freak out like crazy... (it basically assumed i was pressing buttons.)

If it's not in your pocket and it's doing that, I would say it's fubar'd and to get a replacement.

 

Dont bother my eris did it and so does the incredible. Tune wiki seems to deal with it ok. Also if you plug in headphones before starting the music app it seems to help sometimes.