TIM = Telecom Italia Mobile
It is an official BlackBerry OS. However, it is NOT the official Cingular OS, so if you do have a problem with your BB and you need to call Cingular tech support, they will not support you if you tell them you have that OS; likewise, if you take your BB in to a Cingular store for support, you could have a problem.
That said, many many BB users use other OS offered by other carriers and they work fine.
If you are not comfortable doing such, you need to reload your Cingular OS from the Cingular website:
http://www.blackberryforums.com/rim-...downloads.html
For your issue, I think all this a great deal beyond your need, sort of like going into surgery with anesthesia for a torn finger nail.