Flash Player causes Firefox to slow & won't play

I have a new hard drive with Windows 10 so I'm reloading all of my software. I reloaded the latest Firefox and then discovered I needed to load Flash Player so I did that noting that it was specifically for Firefox.

After installing, it has been a nightmare. Whenever I go on-line to any site, I get a flashing (about every 5 to 10 seconds) brief error message which, I think, is about a running script. I have "caught" it fast enough to stop the script but it has made no difference and the problem continues.

What's more, I cannot load a live video.

I went to Edge (which I didn't want to do) and found that Flash Player is already loaded on it and it works fine.

So I uninstalled Flash Player for Firefox and I can go on-line just fine but I can't view any live videos.

For what it's worth, my Flash Player on my notebook is working fine with Firefox so this is something new with the new hard drive and new software installations.

Oh, I did have to upgrade my virus protection. It's TrendMicro Maximum Security.

Flash Player is conflicting with something or something is conflicting with Flash Player, but I can't use it with Firefox. I have been through all of the suggested steps to make it right and nothing works. Right now, I don't have it installed as I need to get some work done.

Would appreciate any help. Thank you.