[sloboy]

FWIW...my phone was doing the same thing, and I tried to turn it into sprint, but because the case had a small crack, they wouldn't let me exchange it.

So....I took the whole phone apart and used some electronics cleaner and a Q-tip on the keyboard plug, and reseated it firmly, and the problem disappeared.

I don't recommend this fix unless you are already out of warranty/no insurance/etc, but it worked for me.