iPhone shuts off since 3.1!!

[SweepeR]

Ok ever since I updated to 3.1 my iphone keeps shutting off on its own. It shuts off and I have to power start it at least 3 times a day.

waht the hell is going on

[Hawk]

It's a bug in 3.1. Mostly 3G users are experiencing this. The main fix for it is to restore the firmware and setup as a NEW phone- which means back up all your bookmarks, notes, pics, etc. before you do anything else.
There is a thread on the Apple forums about this that last I looked last weekend, was over 25 pages long. Apple is slightly aware of the problem, and if you talk to an Apple tech, they will tell you to do the same thing.

In my experience, the problem is due to running out of available RAM.