This happened to me about 5 times on Sunday and once the following day. I know the amp was getting the turn on signal because I could hear the alternator whine.

I am running 2.0b7 Consumer with no other kernals.

A sync may have been what "fixed it". Also, I had just applied more wendy filters (ie changing the properties of some tracks while uploading other songs) prior to the problem surfacing - but this may not be related.