sabel

Im having a small problem.
Bought the phone 2 weeks ago, sometimes it is locked, and unlock itself, then 5 sec's later locks again. It does this 3, 4, 5 ,6 times, then stops and can do that after some minutes, or just in the other day.
I've been to the shop, and they can only send to warranty, because it's un undetected error. ( the phone did nothing when i went there).
Have anyone had the same problem?

Thanks, and sory for the english.