Alright I want to ask this question to everyone. I've joined in on trying to fix this issue and been working for almost a week on this trying to think of everything that I can think of. Right now I really haven't gotten anywhere. But I do have a work around that keeps HTC Messages as the default texting program and you can send/receive/view MMS through the Arcsoft program using WM6.5.3 with Sense 2.5. I decided to go this route because even though we were trying to find a fix for this you still can't view MMS in the HTC Messages program.
I love Sense 2.5 and the HTC Messages program so I wanted to come up with away to keep them both on my phone. I think what I came up with has done this. I talked to HTC and they said that they are working with Sprint still with getting them a working WM6.5.3 to worki correctly with their Phones and their network. So I think until this is fixed on their end I will be using what I came up with. I know that this thread was for trying to find a fix for this issue so I don't want to post what I came up with unless people would like to see what I came up with. If you would like to know just let me know.