Galaxy S2 won't connect to network with a specific SIM after update to ICS

Hi,

I've recently upgraded my S2 i9100 to 4.0.1 (I9100XXLPQ) from 2.3.6 and my Orange SIM does not connect to network anymore (it says "emergency calls only"); manually selecting the network doesn't work either. It worked prior to update and I've tried several roms/modems without success.

Here's the tricky part: this SIM works on my other phone just fine, and other SIMs (even from Orange) work perfectly on this S2. :silly:

IMEI is same as on back of phone..

Any suggestion?

Thanks in advance!

Ok, so I went to my local Orange Shop, have them reset my account, change my SIM card, payed my bill (to exclude every possibility that it could be a network issue :angel. Aaaaaaaaand.. it was still not connecting to network. Went to a "pro" guy to have it reflashed. Same problem.

After thinking to smash it into a wall, turn acid on it and put it on fire, I've decided to play around with phone's settings (though it made no sense since I've reflashed it a few dozen times, each time with different rom, so settings would be reset).

So I've deactivated the PIN request on start-up. Aaaaaaaand.. it works! It connects to network, to internet, to everything. If I switch the PIN request back on, it doesn't work.

So it works without PIN request, doesn't with PIN request. What in the name of Chewbacca is happening?

Cheers!