that’s usually a certificate thing ?, but make sure he actually types in the address in the bar, not click on a link, and it should be www.va.gov that he types. Usually you can add an exception or go anyway. Could be level of cookies accepted? what does the popup say?
I had a problem with firefox a while back and simply uninstalled it and reinstalled it. If you decide not to save your preferences, etc, you should export your bookmarks first...If pages are bookmarked (I have a lot) then I export them as a list (on menu bar/bookmarks/show all bookmarks/click on import and backup/ export as html/save the file).
He typed in www.va.gov .... there was this popup from Firefox and the line in there said “Get me out of here” with no way of by passing it ... we did the security thing and other stuff ... even IE wouldn’t let him in. I think he just went to Google and typed in VA and I he got in via some link. No problems after. There were a couple of well known sites that FF blocked also.