It should work if Firefox has its default PDF handling setting of "Open in Firefox". This article describes where to check that: [[View PDF files in Firefox or choose another viewer]]. If that choice is not available, or if PDFs save to the temp folder and open from there, here are a couple other things to check: '''Built-in PDF Viewer disabled by preference?''' (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ''More info on about:config:'' [[Configuration Editor for Firefox]]. ''The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.'' (2) In the search box in the page, type or paste '''pdfjs.disabled''' and pause while the list is filtered (3) If the '''pdfjs.disabled''' preference is bolded and has a value of true, double-click it to restore the default value of false '''Built-in PDF Viewer disabled by policy?''' This would be most relevant to a computer which is managed by an IT department. In a new tab, type or paste '''about:policies''' in the address bar and press Enter/Return to load that page. The normal thing to see here on the "Active" panel is "The Enterprise Policies service is inactive." Do you have any policies listed here and, if so, do any of them refer to PDFs?

"Open in Firefox" did the trick - I wouldn't have thought it would be so simple; Thanks for the help!