My Streak has done this a few times in the few weeks I've had it, but at the moment it's chewing through power at a stupid rate every day. I assumed it was something I'd downloaded so was considering a hard reset one evening this week...
I have found android.process.media often chomping 85-99% of my processor so I keep killing it which helps, but obviously I don't know the underlying problem. A quick Google showed that someone else had one particular file that was causing it, but deleting the same file didn't work for me.
I'll let you know if a hard reset helps, otherwise it's back to the O2 shop