Had to fix one of the computers at work. I won't say WHO.
Original complaint: customer email with attachment not opening.
Foxit PDF reader was not working at all.
Uninstall and reinstall Foxit.
Uninstall Foxit, bite the bullet, and – even though I hate Adobe – install Adobe Acrobat PDF reader.
Email works, attachment opens.
Routine cleanup -- ran Malwarebytes, just because. Client uses Avast antivirus because, "Well, I always have!" He's an old guy. So am I, but he's an even older guy, so whatever.
Malwarebytes finds like 500 suspicious / malicious files. Looks like this person gets like all their news and information from chum box click-bait junk sites. So I quarantine all those files because who has time to sort it all out?
Did I mention this machine is running XP, and a pirated copy of the student version of Autocad, and a really iffy looking installation of MS Office, and . . . Oh hell, what do I care? The attachment opens now.
Okay bye. And don't click those sidebar- and bottom-dwelling links!
"Well, I always have!..."