Hello Rabb02, did you try to check it in safe mode ? Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

thank you

I still get the same error

That is likely caused by a JavaScript that runs on the page and that check the onbeforeunload event.

Facebook may have changed their pages to prevent dataloss if you leave the page without saving.
Most online email editors also show this behavior.

Is this the same thing as somone suggested as an Exit Splash? Because I tried ad-block plus and it didn't help.

If it is why would would it all of a sudden show up especially on Facebook Pages for companys?

I don't have or want any type of "social media" type account, but I do visit them sometimes if something turns up in a Google search that I need. The common denominator for me is it always has something to do with Microsoft, a coincidence I'm sure. However, Firefox developers, living in their bunker deep underground somewhere with no Internet access, have done nothing to fix or explain this VERY long-standing problem. Even safe mode does not work around the problem. The work-around is to right-click on the back arrow button and select the link you want to go back to.

How about resetting your Firefox? But before you do, save all your data from Firefox using steps provided at: https://support.mozilla.org/en-US/kb/firefox-sync-take-your-bookmarks-and-tabs-with-you and then follow the below guidelines:

1. In your address bar type about:support
2. On the page appeared, click on Reset Firefox

Let us know if the problem continues. :)