@YoDude:

Do you use a SIM?

Yes, I do use a SIM. Do you think it could be because of a bad SIM card? I have been using the same SIM in my old phone for about six years now; I'm not sure I want to change it because I would have to change my phone number (among other hassles that outweigh the disadvantage of just not using a N900).

you can get a replacement SIM from your operator if you are on contract it should be free i recommend it i upgrade my SIM once a year