Active sync quit working, but version 4.5 does work?

[robocyb]

I have been using activesync 3.7 with no problems until this week. All of a sudden, my partnerships have been removed from the computer, and version 3.7 will not establish a new partnership. Tried hard reset, removing and re-installing software. Nothing worked. I then tried version 4.5 and it worked. However, the problem is, I need to use version 3.7 to sync with Act 2007. It doesn't work with version 4.5. Has any one else run into this? Does any one have any idea what installation caused this problem? I removed the DST update and it didn't change anything.

any suggestions?

robocyb