"Unregistered sim" after upgrade to 2.1

Hi guys,

After an upgrade to the Sensation XE, I decided to pick up a 2.1 rom, Odin and attempt an update...

Phone was originally locked to T-Mobile (UK) which i've unlocked.

After installing the new Firmware, I was able to use the phone with no issues on O2 for about a week. I've switched the phone on this morning and i'm getting no signal and a status of "unregistered sim".

Incidentally, when I installed the ROM and switched the phone on for the first time,the lanuage was Dutch. Could this be part of the problem as i'm using UK network sims?

If it comes to the crunch i'll downgrade back to Cupcake...which i'm also unsure how to do.

Can anyone point me in the direction of a ROM that will be compatable with UK carriers?

Thanks in advance...