If you're familiar with running SQL scripts, you can try running these two in QueryAnalyzer:
1.
use unitydb
update subscriber set objectchangedid = 0
2.
use unitydb
update mailboxstore set objectchangedid = 0
After that, go to \CommServer\Techtools\Dohproptest.exe (it'll ask for a password, but you don't need it), click on the button that says something like "55 monitor", it should be in the bottom right hand portion. That will bring up another dialog box. From there, click "Total Resync".
See if that does the trick.
