I've written to zimbra support with all logs of our BES server and ZCB.
We have experienced lock of BES server ONLY for some users (that doesn't receive mail and sync calendar).. after several restar of machine (no BES service) seems that this users starting receive new mails..
On your pdf files about installation of ZCB, there is a support case for MSPST32.dll that cause crash/deadlock of the connector.
We have currently 10 users to this new server, but I don't think that is a "large number" that can cause this issue..
I've already open a support case on the portal with all logs about the last two days where the problem come..
Hope someone of support can help me, because after a new clean installation the situation is very unstable than before, and my boss is become very rustrate about losing appointment and mail..