Firefox Support Forum

Summary of my current relevant software/hardware:

FireFox (UK): 113.0.2 (64-bit)
Windows 10 Pro(UK): 
 Vers.: 22H2
 Installed on: 2021-01-23
 OS build: 19045-2965
Lenovo (laptop): 
 ThinkPad X1 Extreme Gen 3
 Processor: Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz 2.59 GHz
 Installed RAM: 32.0 GB (31.8 GB usable)
 System Type: 64-bit operating system, x64-based processor

My problems with FireFox 113.0.2 started when I began to download some Affinity V2 videos. Some of these were rather large (over 500MB) and I noticed that several were being downloaded at the same time (which was no surprise). However, after sometime I noticed that only one of the videos was completely downloaded and the others were just stopped. Then, when I looked at the task manager the number of FireFox instances was increasing: ...,5,6,...18,..

Of course, I thought I could fix the download process but all my efforts failed; e.g. after a restart of windows and execution of FireFox the same videos were still in a "hold" state and many instances of FireFox were being executed. After a frustating night of failures I finally decided to restore an older FireFox using my Acronis backup/recovery software. My last Aronis backup of my entire system was made on 2023/04/07 with the most recent version of FireFox at the time which worked fine when downloading several large video files at the same time.

I only included the C:\Program Files\Mozilla Firefox' in the restore since I have installed a rather large number of new apps and updates after 2023/04/07. This also failed -- my add-ons, bookmarks, etc. in this restored version were all missing and before I could stop the recovery process, the restored FireFox was updated to the latest as of today (2023/06/01). And of course the problem had not be fixed.

So finally to my request: What directories, files do I need to restore, from the 2023/04/27 backup with all of its features at that time -- this is important, and how do I stop it from upgrading to a newer version?

I would be glad to provide additional information if needed :-)

Bought a new computer that was supposed to come with Windows 11, but came with Windows 10 and right to upgrade. Set up computer, downloaded Firefox, and it ran fine. after a couple of hours, ran the upgrade to Windows 11. Firefox stopped opening. uninstalled then reinstalled Firefox several times, but each time during installation get the following message (image below):

"C:\WINDOWS\SYSTEM32\MSVCP140.DLL is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support. Error status 0xc000012f."

Have tried installing with and without defaults, and refreshing instead of reinstalling.