NAV segment integration with Outlook

We use NAV 5.1 with Serenic Navigator for Nonprofits. Two days ago we were using Segments perfectly with the Email option. but then just yesterday, when anyone at our company tried to run segments we received this error "Either there is no default mail client or the current mail client cannot fulfill the messaging request.  Please run Microsoft Office Outlook and set it as the default mail client"

I checked and Outlook is checked to be the default mail client. Then I thought it was the NAV db.  maybe it was corrupt, or someone changed a setting.  But I tried the similar segment in a test db running NAV, and the same error occured.  Which made think that it is not a NAV db issue because 2 separate dbs were getting the same error message, and the likely hood of both dbs geting changed or corrupted the same was is highly unlikely.

It seems like the issue is the Outlook permission letting other applications access the mail client.  But I'm not sure.

My questions is how can I get Outlook to integrate with segments again so I can communicate with my clients?  Is there a setting in NAV that allows me to choose Outlook for segments?  Remember this function was working 2 days ago just fine.