I had the same problem, and ended up fixing it myself. I know this is my first post but please trust me. This .cab also fixes the problems in WinMo 6.5 beta as well.
- Run the .cab that I have attached to this post and
- Go into settings
- At the bottom click the system tab
- Run the "Update Profile" program that is now listed
- *Run Update PRL
After these simple steps you should be back in business.
This cab also fixes the SMS Character limit and MMS problems for Sprint.
Sprint assumes that you have a stock rom, so to them yes, your phone is working fine.
*is not required but helps you with better service.