Hi, Please try a Ctrl + F5 refresh of the page. This may also happen if you are inside a private network and and port blocking is in effect. ............................................................................................................................... Useful links: [https://support.mozilla.com/en-US/kb/Options%20window All about Tools > Options] [http://kb.mozillazine.org/About:config Going beyond Tools > Options - about:config] [http://kb.mozillazine.org/About:config_entries about:config Entries] [https://support.mozilla.com/en-US/kb/Page%20Info%20window Page Info] Tools (Alt + T) > Page Info, Right-click > View Page Info [https://support.mozilla.com/en-US/kb/Keyboard%20shortcuts Keyboard Shortcuts] [https://support.mozilla.com/en-US/kb/Viewing%20video%20in%20Firefox%20without%20a%20plugin Viewing Video without Plugins] [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder & Files] [https://developer.mozilla.org/en/Command_Line_Options#Browser Firefox Commands] [https://support.mozilla.com/en-US/kb/Basic%20Troubleshooting Basic Troubleshooting] [https://support.mozilla.com/en-US/kb/common-questions-after-upgrading-firefox-36 After Upgrading] [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes] [https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins Troubleshooting Plugins] [http://kb.mozillazine.org/Testing_plugins Testing Plugins]

Haven't looked through all of the links you sent yet, but the chat will work when I use IE8 on the same pc. Also, it worked fine with Firefox on a previous pc I was using. I'm guessing it may be some app or add-on or something that I'm missing. Maybe a setting I've not run across yet. Still looking for the fix........... Thanks for the help

If you suspect an add-on then the fastest way to isolate the cause would be to try [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode.]

Tried Safe Mode and it still doesn't want to show that pop up window for the chat. The Yahoo Mail tab name even flashes that I have a chat available from someone, which usually means I have a minimized window at the bottom of the screen, but I don't see anything to reply to. The answer still evades me. Thanks again for trying to help me.

I hope you are able to find a quick solution. One last thing that comes to mind is to try toggling the Messenger options between small window and tabs and also the conversation style.