Fyi: July version 52 came out for XP. You should update for security issues. As well if not checked for XP Updates 1 was released a month or so ago .

Let us know then about your saving files.

Thank you Pkshadow.

The file saving problem is Solved. Evidently changing mp4 Back to save file did the trick. But that leaves as an issue that FF allowed that option to change for no reason.

I deliberately did not update to FF 52, but as I cannot now remember why, I will try 52 (again). I have resisted doing this because going back to 51 while preserving my profile is tricky. It is necessary to save the profile, then do a complete uninstall, then restore the profile (to a newly created C:\Documents and Settings\ral\Application Data\Mozilla\Firefox\Profiles\), then reinstall 51. [I think I finally have this just right]

Did you say there is a new update to XP? It was 2 or 3 months ago, maybe 4, that I noticed that XP was updating again, but I will try to check this out.

I will mark this Solved, but have found that I must respond before, as marking Solved prevents further posts,

Update to Pkshadow: An afterthought: maybe going to FF 52 will solve whatever is causing FF to crash 10 or more times per day.