Originally Posted by Bakaboy
In my case I usually have it on USB but it randomly switches to FM now and then. I can count the number of times though (4 times IIRC), so its a fairly rare occurrence. Doesn't bother me much, but I do have the WTF moment everytime it happens.
Someone had a similar experience with this and was off the walls pissed about it... turns out, his favorites buttons were changing source, make sure you're not just accidentally hitting that :)