KB931832 was automatically applied to our server, and all four Windows Mobile 5 devices stopped syncing in 90% of the tries right away. Two is MDA-I, one is MDA-II and one is MDA-3. So it is not a specific BlackBerry problem.
As a workaround, we are now syncing every 5 minutes so you get your mail at least once a day.
Reversing the patch was not possible, since we first tried to install W2K3 SP2. Obviously this one removes the uninstall folder.
We did find the kb931832.log however.
Since this is the second time this year that a patch caused our SBS server to give production problems, we have disabled automatic applying of patches.
Any hints from any one on how to get Windows Mobile 5 going again?