Can you attach a screenshot? *http://en.wikipedia.org/wiki/Screenshot *https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem *Use a compressed image type like PNG or JPG to save the screenshot *Make sure that you do not exceed the maximum size of 1 MB ---- Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (Firefox menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem. *Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance *Do NOT click the Reset button on the Safe Mode start window *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes See also; *https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware ----- You can check for problems with the sessionstore.js file in the Firefox profile folder that stores session data. When sessionstore.js is deleted you lose App Tabs and Tab Groups and open tabs and you will have to recreate them, so if necessary make a note or bookmark them. You can use this button to go to the current Firefox profile folder: *Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder) *http://kb.mozillazine.org/Profile_folder_-_Firefox