I'm seeing this too, on my Galaxy Note. I generally use Poweramp exclusively in my car, via bluetooth connection (Ford Sync). My Note is running ICS. It appears that this 'restart track at the beginning' happens if the phone is locked (mine is locked with a passcode). I've also tried this with the phone unlocked (and the Poweramp screen up) and the track doesn't reset to the beginning. With the phone disconnected from Sync, hitting Play resumes the track from its current position. I'm not sure when this behavior started, but it's pretty recent - probably with the last Poweramp update.