I'm not sure exactly what the site is doing. Is it attempting to add a bookmark in Firefox or in Facebook?

For reference, the built-in Firefox dialog is attached. Is that the one you're getting? (Your OS will affect the window frame appearance.)

Yes, then it just hangs the system. I have listed all my extensions and add-ons on the right.

I don't know whether there is a connection between the bookmark dialog and the lockup.

It's strange that you have two versions of Shockwave for Director. Can you disable the older one? Or disable both, if not needed for this site.

There are some compatibility issues between the latest Flash player and some Firefox add-ons or settings. You might consider disabling the new protected mode in Flash 11.3, since that feature is currently being debugged. See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

Start Firefox in Safe Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes