Enterprise Vault HTTP-Only Outlook Add-in v11

Hi all,

When I deploy the MSI Outlook add-in of Symantec Enterprise Vault version 11 to a computer that has a previous version of Enterprise Vault Outlook add-in installed. Outlook will stop spontaneously, all open items are not saved.

I am using the following command-line:
msiexec /i "Symantec Enterprise Vault Outlook Add-in.msi" /q Reboot=ReallySuppress

When I try to first uninstall a previous version of EV Outlook add-in from a computer, Outlook crashes too and no open items will be saved.

I've searched different forums but I cannot find a solution. Can someone help me? Much appreciated!

Many thanks