Well that's a drag. I can't get W11 into safe mode with networking. I called Dell (laptop), tech support said that it's a known problem, doesn't know if they're going to fix it. Tried to pass me off to M$ but I pointed out it's their responsibility to get their hardware working with M$ software and in the past, safe mode with networking has worked. :-(

Did you follow the "Don't see the block icon?" instructions?

You could also try running in "Windows Sandbox" if you have Windows 11 Pro edition.

Well I finally got the system booted into W11 Safe Mode with Networking. It works on wired networks but won't work over wifi. And FF seems to work properly, does not hang. And when I boot normally, FF hangs on some websites. And now when I check about:third-party I see only one app, the roboform module. The other day I saw about four, wonder where the others went.

Anyway, I don't see how to disable that module on the about:third-party page. And it seems strange that when I run FF in safe mode, that disables roboform, but does not disable the module?

Also, on the system that FF seems to run, it doesn't have Total Defense, but it does have roboform. Seems contradictory from what I see on the other systems.

I just tried a full Total Defense uninstall (which includes a reboot) and now FF seems to work like it's supposed to. It doesn't seem to hang on the sites it hung on. And I reinstalled TD and now it hangs on some sites again. So it looks like an incompatibility between FF and TD.

What could TD be doing that's messing up FF, but not Chrome and not Edge?

Huh. Last time I tried an uninstall of TD, it didn't help, so maybe it was operator error.

Well I think I've finally found the setting causing the problem, thanks to all the pointers people gave me.

It looks like it's a setting in Total Defense, if you click on the "Security" tab in the left column (2nd from top), then Settings (2nd in the top row of icons), then Scanner, you'll see two toggles.

Autoscan On seems to cause FF to *sometimes* hang on some web pages. Other pages seem to work OK. And even sometimes the problem pages seem to work OK, and that's why it took so long to track down. The problem was a bit intermittent.

Autoscan says it's "Real time detection and removal of viruses and spyware" And I have always set the Scan Options slider to "Recommended" (vs low, high, custom). There are a bunch of items under Settings when you choose Custom I'll play with.

Now the question is why the Autoscan causes a problem with FF but not for Chrome and Edge.

Anybody have any ideas?

Another setting might also be a problem. If you set the above slider to "Custom" and turn off the push button "Access network files using current logged-in user impersonation", things sometimes run much better. According to TD, this is used only for accessing network drives, so it shouldn't have anything to do with this problem so maybe it's a matter of intermittency.

Well after a week I'm no closer to finding anything that correlates to FF working or not. Whatever I try doesn't seem to be consistent with working or not. Even what I had thought concerning disabling or removing Total Defense doesn't seem to correlate reliably enough to declare it a problem. The only thing that seems consistent is holding down the 'SHFT' key when doing a refresh after a page is hung. That seems to cause the page to come in when it didn't before. That to me would point to a problem in FF. I don't know what else to try other than go to a different default browser which I really don't want to do.