Originally Posted by
ReGeNeRaTe I found the problem. It is the app. 8IconDock v1.1
I removed it and the sun shines.
Damn I got used to this app

Try backing up the iPhone to iTunes, reset to factory settings, re-install the firmware, reinstall data and apps from backup, and then install the app again.
If the problem recurs, you know what to do. Might be nice to report the problem to the application author.