Firefox 52 no longer working on XP

[NotHereToPlayGames]

Try the PortableApps Portable Legacy 52 and see if it launches.  It will not affect other Firefox installs/profiles.

https://portableapps.com/apps/internet/firefox-portable-legacy-52

[NotHereToPlayGames]

If it DOES launch, then you should be able to REPLACE all of the .exe/.dll/etc root dir files/folders of your "installed" version and it should now also launch.

[NotHereToPlayGames]

If it does NOT launch, then clench your fists, pound one sternly but in full control of anger level on desktop but make sure you miss keyboard and mouse, grab something in the other hand and controllably throw something without breaking it or anything it hits, raise your voice level approx 15 decibels (whereas 30 decibels is the increase of a raging uncontrolled shout), and shout out this phrase, "Curse You, Malwarebytes, You Did This!"

[NotHereToPlayGames]

Oh, and I didn't think about asking this earlier, but when you tried to uninstall Malwarebytes and it resulted in your computer REBOOTING itself (prompting a Safe Mode uninstall of Malwarebytes), was Firefox OPEN when Malwarebytes uninstall crashed your system into a reboot?

[Dave-H]

No, Firefox was not open when I uninstalled Malwarebytes.
I hardly ever use it now.

Thanks for the link to the portable version, I will give it a try and report back.

[Dave-H]

OK, it's fixed!

The portable version worked fine, and in fact if I ran the firefox.exe in the portable version's program folder, rather than firefoxportable.exe, it opened fine using my normal Firefox profile!

So, I started comparing the two installations, and found that some DLLs in my Firefox program folder appeared to have been disabled by renaming 'DLL' to 'D~L'.
That's my normal way of disabling a file, changing the middle character of the extension to '~'.
Why I had done that is lost in the mists of time in this case, but one disabled DLL file stood out, and that was msvcp140.dll, which is a C++ Runtime file of course.

That reminded me that I had recently updated my C++ 2015-2019 Runtime to 14.29.30139, following a recommendation elsewhere on MSFN.
Thinking perhaps this could be the issue, I simply renamed the msvcp140.dll file in the Firefox folder back to normal, and everything came good!

So, I guess the new system runtime file versions may not actually be compatible with all programs, so I will now be on the lookout for any other seldom-used programs which no longer work.
Thanks everyone for the help as always!
Cheers, Dave.

[NotHereToPlayGames]

Sweet!

I'm so huge into *everything* PORTABLE that I have never installed *any* C++ runtime.  None.  Naughta.  Zilch.

I prefer to manually place the SMALL HANDFUL of .dll's that some programs require to be SELF-CONTAINED within that program's OWN ROOT DIR.

It's almost always the same two or three or four .dll's and even though my setup has those existing as "duplicates" across my hard drive, it's still MUCH LESS space than the full runtimes.

Kind of like how several .dll's land in the root dirs of things like Supermium, Mypal, Serpent, etc.