Sometimes extensions can affect pop-ups. Could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any difference?

Also, could you check the various hidden settings for popups using this method:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste popup and pause while the list is filtered

(3) If any of the preferences are bolded and "user set" try right-clicking them and using Reset to restore the default value.

Such changes might not take effect immediately, so you might need to exit out of Firefox and start it up again before testing.

Thanks for the suggestions, but neither worked. However, I did get my problem fixed. The problem was with AdMuncher. I had added the Pogo game sites, but had a mispelling.

Thanks for your help.

krys1202