Can't use basic phone functions after trouble with CallMe

Hey guys,

I have a jailbroken iPhone 2G (OS 3.0) and used to be very fond of the CallMe-app (installed from Cydia) which displays contacts' faces on the home screen as speed dial buttons.

Yesterday I tried to delete one of those contacts and ever since I cannot

- check my mails (opens mail application but goes back to home screen after trying to open specific e-mails)
- open contacts (every click on "contacts"-button will take me back to the home screen within seconds)
- call contacts (every click on "phone" will take me back to the home screen within seconds)

What still does work: Safari, Calender (though I am no longer 'reminded' of events), camera etc.

All that I have tried so far (except for failing to find a proper response to my exact problem) is to sync my contacts with Outlook (what I have never done befor, meaning I would lose all my contacts if I don't find a solution to this problem... stupid, I know...) - but that didn't work. After backing up the phone iTunes said that it couldn't sync contacts because the phone had been disconnected (which, obviously, it hadn't).

I'm a little lost/anxious.

Can anyone help me?

 

P.s.:

Oh, and: I have deleted the CallMe-app via Cydia - the app's button has then disappeared but the contacts' speed dial buttons remain...

Plus: I have, of course, tried to restart the phone several times, without success.