I also have a 6800 from Alltel. This happened to me the very first day I had it without adding anything to the phone. I believe it has something to do with the Mem card. I discovered that if I remove the card (which by the way was purchased and installed by Alltel) it does not lock up. If you have a mem card installed you can try to eject and reinsert the card... that has worked for me as opposed to doing a soft reboot.
