I have a co-worker whose Vibrant refuses to wake up after the proximity sensor blanks the screen during a call. Likewise, when her phone blanks the screen after the phone has been idle for a little while, it can't be woken back up. The only solution is to remove the battery, replace it and reboot.
T-Mobile has replaced the phone once already. The new one has the same behavior, and it's getting worse over time. Any suggestions on how to fix it?