Hey man. I had this exact same problem. But luckily, i solved it . This is how i did it:
1. Backed up everything from my N900
2. COMPLETELY formatted the device. I don't mean reflashing. Connect your N900 to you computer in mass storage mode. And format it, but don't do quick format.
3. Reflash it with USA release firmware. That one solved the problem for me. I live in Europe and i tried both Europe and Global release, but USA release was the only one that worked.
4. Make sure that when you reflash you DON'T back up any programs. Install them one by one.
Reply back if you solved your problem.