[P990i] Problem after debrand

Hello there,
I've got SE P990i with polish Orange's software. I've debranded it, upgraded it to R6E28 Generic World 1 and now my phone is occasionally losing GSM signal... Only restarting device solves this problem. I must do it about I didn't do GDFS backup (silly me...). I wanted to change CDA by editing my current GDFS backup (which I did after debranding), but when I edit (with HEX editor or GDFSedit) all needed strings (i. e. from CDA162007/1 to CDA162008/46) after writing that file to my phone it says that I have CDA162008/4... '8' is missing! I've also downgraded soft to R5A17, still same problem :/