I never would have thought to open the installer in Firefox. Isn't the online installer a separate application? How would you open it in Firefox? Regardless, really glad you got it working!

The XLN installer probably uses Mozilla libraries as part of its interface.
 
Even Sonar and/or Command Center use 3rd party web libraries (in this case Google's chromium embedded framework [CEF] ).
 
When applications use these libraries, they'll inherit settings/certificates from their main browser (i.e. Mozilla from Firefox, CEF from Chrome).
 
Most applications use CEF nowadays; older ones a wrapper around Internet Explorer (obviously Windows only apps). However this is the first application I've seen that uses the Mozilla libraries.
 
Nicely found Craig though - Firefox definitely wouldn't have been on my radar as a possible candidate.
 
M.

mrpippy2
I never would have thought to open the installer in Firefox. Isn't the online installer a separate application? How would you open it in Firefox? Regardless, really glad you got it working!

Sorry, guess I wasn't clear. What I meant was I was trying to connect to the installer through Firefox, but Firefox showed the web site as not secure. Firefox is better than other browsers at telling you why it's upset, and its security warning said there was a certificate it didn't recognize.
 
I then went into Windows and opened Manage Computer Certificates, which is how I deleted the certificate.