hello, can you try to replicate this behaviour when you launch firefox in safe mode once? if not, maybe an addon is interfering here... [[Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems]]

Separate Issue; Your System Details shows; Installed Plug-ins Shockwave Flash 23.0 r0 Shockwave Flash 19.0 r0 <br>Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer. Flash: Grab the uninstaller from here: '''[http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html Uninstall Flash Player | Windows]''' '''[http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html Uninstall Flash Player | Mac]''' Then reinstall the latest version. '''Note: Windows users''' should download the '''active_x''' for ''Internet Explorer.'' '''and''' the '''plugin''' for ''Plugin-based browsers'' (like Firefox). '''Note: Windows 8 and Windows 10''' have built-in flash players and Adobe will cause a conflict. Install the '''plugin only.''' Not the '''active_x.''' Flash Player '''Version: 23.0.0.162''' Flash Player (Linux) '''Version 11.2.202.635''' https://get.adobe.com/flashplayer/ Direct link scans current system and browser '''Note: Other software''' is offered in the download. https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) '''Note: Other software''' is offered in the download.