Exact same problem has started with my sensation today. no idea why, was down to 25% battery by 13:00 this afternoon after very minimal use. have since charged to full when i got in from work, and have lost 15% in the space of 10 minutes.
the sync function has stopped working, and random shut downs have started. 3 error reports sent to HTC so far today.
had sensation less than a month...not impressed!!!!