IPhone :: Voicemail Password Keeps Popping Up After Calls?

Everytime I end a call a screen will show up asking me to enter my voice mail password. If I click cancel it will show up again once more, another cancel, and it will go away. But if I enter something and click ok, it will just keep coming back.

Here's the thing though...I don't have a voice mail password.

My visual voice mail does not work and my phone will not tell me if I have a voice mail or not. I called my voice mail and went to the option to turn off my voice mail password, yet it didn't do anything.

I tried making a password then getting rid of it, hard reset, restore, everything and nothing seems to work. I was hoping iOS4 would do something to fix it but no luck.

Also, this screen will also show up if I have no service and then regain it. (It also tells me if I have a voice mail only if I have no service, which is pretty much never).

Any ideas?