What is going on??

This is my story...

Got one of those Turbo sim and everything was working fine (iphone 3G). After that...I upgraded to 2.1 and the phone was not finding any network.

Then for long time I could not downgrade. I did finally with winpwn back to 2.0.2 and the phone was working again..... for half a day...then just in a sudden I lost network again...and now for two days can't do anything about it.

I tried to restore again the 2.0.2 firmware with winpwn.... tried to upgrade again to 2.1 and downgrade as I did in the first place...nothing.

Moreover, (don't know if that is important) before that I had to remove the sim card (even with the Turbo sim) when I was connecting to i Tunes cause it was writting that the sim is not supported.... now... nothing like that... it connects properly.

Any ideas what could go wrong?? Maybe something is wrong with Turbo sim?? How can I check it is not damaged somehow??

Thanks in advance.