Have a good working copy of the Powershell code necessary to actively trap 8230 events on remote servers and execute PowerPoof against the Calendar in the suspect mailbox. A single instance is required for each server. I'm running against four clustered 2007 servers.
Right now the code is contained in two ps1 scripts. It also requires PSEventing to be installed. The first script calls the second one in a new Exchange Powershell so that get-mailbox can be executed safely. It then exits that shell and returns to watching for new events.
I would suggest executing the main script (get-logevent.ps1) from a non-Exchange Powershell. I only say that because I change the title of the window to the name of the server being watched and that function doesn't work in the Exchange Powershell. Here's a link to the downloads:
The code is raw but it gets the job done.