No luck either way.
Looked on another machine (new laptop, recient install) not connected to our SBS server just to see it it was server permissions related (Should not matter as I’m in the admin group on the sever) ? The laptop already has the correct association and was not a problem to change the default or add another program to the open option.
Just noted the laptop has not been recently updated, running V5 5.6.31003.3365.
Desktop in Question? V5 5.6.31009.15315