OK.. I found some other methods that people have done. Hopefully at least one of these will help.
Some people mentioned that you should uncheck the "Enable Advanced Network Functionality" (Start/Settings/Connections/USB to PC).
So these are the methods I found online. Deleted active sync profiles, disabled firewall, reinstalled activesync, hard reset (you can use Sprite backup to restore contacts) Try other methods first though, hard reseting your device should be one of the last.
There's also this. Go to your PC and go to:
C:\Program Files\Microsoft ActiveSync
then find :WCESMgr.exe: right click in the mouse and doble click "run as" then type your login and you should be able to get back your sync...
Lastly... you can download a cab file called "ActiveSyncMode.cab" (sometimes named ActiveSyncMode.sa.cab)
You install it and run it (start/programs/activesyncmode.exe)
you can download it from
here.
Hope at least one of these work.