This issue originally came up in early 2010, but I was reminded about it the other day when a colleague asked whether the issue still existed or not. I looked back over my blogs and discovered I didn’t write about it the first time around, so … here goes!
This issue only exists with Outlook 2007 on the Enterprise Vault server. It does not exist when Outlook 2003 is installed. I do not know about Outlook 2010 – and that is currently not supported anyway (on the EV server).
With Outlook 2007 installed, if PST migrations are done and/or Vault Cache is enabled for end users then a large number of entries may build up in the registry under the following location:
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Catalog
The entries will look something like this:

As you can see from that screenshot I’m getting a...