What OS did you upgrade too? And did you make sure to delete vender.xml file when upgrading?
Also, was this phone brand new, or is it used. I would try to reload the OS, or if you haven't upgraded to it yet, upgrade to the 4.5.0.124 OS. I just did it on my 8320, and haven't had any problems.
Here is a link to the upgrade and directions, fairly simple, will just take some time to complete.
Newest 8320 OS: v4.5.0.124
Good luck and keep us posted!