Screen flashing "S.O.S." on startup

I had a LG Xenon before that I had to replace because the sensor for sliding in and out failed.  The ATT Store gave me a brand new Xenon for free.  I've had this for quite a few months now and had no problems with it.  I've never dropped it or abused it in any way, and it has been in a case since day 1 of receiving it.  I turned it on this morning and it started flickering morse code for S.O.S. (3 short, 3 long, 3 short).  I took the battery and SIM card out for >5 minutes and put it back in.  This time, I was able to get past startup, but a few minutes later, it went back to flickering SOS on the startup screen (white with ATT: World Phone logo).  I'm just curious if there is a known fix to this or if anyone has had this problem before I take it into the store.  I've just about had it with this phone, ATT, and LG.

Hey, thanks for the reply.  I took the phone in and the people working there said it was a problem with the Firmware, and that there was nothing they could do.  It's weird though, because sometimes I can get the phone to start up.  They said if I shipped it in to ATT they could reflash the phone and it should fix it, but I would have to pay S&H.  It seems kind of ridiculous that I have to pay for a problem in programming/manufacturing the phone.  They also said I was upgrade eligible so that is probably what I'll be doing...