I take it you tried shutting the phone down and re-starting?
If that didn't work, might be worth checking if you have adequate internal storage free.
Failing that, check that some guru on here hasn't come up with a smart idea. In the unlikely event they haven't, you could try backing up your data (contacts, calendar entries etc) and doing a factory reset.
If none of these options work, you should either return the phone or get it repaired (after backing up and doing a factory reset to clear your private data).
If you're in europe and you've had the phone less than 14 days, I'd skip all the faffing about, go directly to option 4 and get the phone replaced with a new one.
