Hi, Please check if this happens in [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] [http://support.mozilla.com/en-US/kb/Uninstalling+add-ons Uninstalling Add-ons] [http://kb.mozillazine.org/Uninstalling_toolbars Uninstalling Toolbars] Safe mode disables the installed '''Extensions''', and themes ('''Appearance''') in '''Tools''' ('''Alt''' + '''T''') > '''Add-ons'''. Hardware acceleration is also temporarily disabled - the manual setting is '''Tools''' > '''Options''' > '''Advanced''' > '''General''' > '''Use hardware acceleration when available'''. [https://support.mozilla.org/en-US/kb/Options%20window%20-%20Advanced%20panel?as=u Options > Advanced]. All these settings/add-ons can also be individually or collectively disabled/enabled/changed in Firefox normal mode to check if an extension, theme or hardware acceleration is causing issues. [https://support.mozilla.org/en-US/kb/Options%20window Options]

For Yahoo mail, see reply from '''''Cww''''' for an explanation and workaround in this post --> https://support.mozilla.org/en-US/questions/924230#answer-323590 Same explanation may apply to other sites not recognizing your installed version of Flash (Add-ons > Plugins > "Shockwave Flash" version); for a workaround, contact the site. '''If this reply solves your problem, please click "Solved It" next to this reply when <u>signed-in</u> to the forum.'''