Reboot loop, but only with Brazilian SIM card

[Guest Kurvenal]

I have a new Orange Omnia. I got it the day before I had to travel. Interestingly, it seems to be unlocked because I have been able to use a T-Mobile USA SIM card without a problem. I am in Brazil for a week and have purchased some local operator (TIM) PAYG SIM cards. The TIM card works fine in my Nokia, but every time I put one in the Omnia it goes into a reboot loop on startup that I can only stop by taking out the battery. I checked on some forums and tried removing the storage card as instructed, but this did not help. It seems to happen when the phone starts looking for a data connection. I have removed the default Orange Internet connection to see if that would prevent it from looking for a data network, but this did not make a difference.

Any thoughts?