default email reader sticks

Apple mail preferences "default email reader": selection list shows every app on Mac Mini even Windows app's on virtual machine. I select "Mail 6.2", but when I reopen preferences it bounces back to "Windows Media Maker.app" which is first app on list. On selection holds, always reverts to first app on list

I have tried deleting mail's .plist to no avail. This only occurs on the Mac Mini, not the MBP.

Mail seems to work OK

Ideas please.

Bill