Nokia 920, unlocked from Rogers, now with Bell.
Also lost ability to send/receive pics in texts. Very frustrating.
edit:
POSSIBLE SOLUTION:
So, I opened up Access Point, and it was showing Bell as inactive. I then manually made a Bell2, I only bothered putting in the MMS APN info I could find. Then I switched to Bell2 just until it said Active. Then I switched back to Bell, and it went Acitve. Then I was able to send and receive my picture messages.
Basically, just make a fake operator in Access point, switch to it temporarily, and then switch back. It should force Access Point to automatically get the newest settings.