2012-05-01 9:04 - edited 2012-05-01 9:05
Thank you for your post and welcome to the forums!
There are a few things that you could try. First try to re-install your phone firmware with Nokia Suite and select Tools > Software updates. You can also try resetting your device, just remember to backup of your phone first with Nokia Suite.
Dial *#7780# to soft reset your device, this will return the phone to factory settings without removing any personal data. If this does not solve the issue, hard reset your phone.
Dial *#7370# to hard reset your device. Hard reset will remove all settings and personal data off the phone, so remember to backup your data first.
When prompted for security code, default code in both cases is 12345.
If the issue persists, plese visit the nearest Nokia Care Point and let them have a look.
Let us know if this helps,