This is why I don't like UM with Outlook integration. Many times with Microsoft updates, something stops working or gets messed up. I'm thinking that the problem is with Outlook. The user's PCs are getting an update that is causing your problem. What that update is? I don't know. Maybe you can start comparing the update history between one computer that works and another that doesn't work with View Mail. Also, there was a small program supplied by Active Voice that completely removes View Mail from the PC because an uninstall doesn't remove everything related to View Mail.