Sebastian, this is not expected. I might first recommend to start Firefox in Safe Mode to see if its an add on or hardware acceleration.

Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

This don't fix this problem. ;(

Maybe there is an option to use teamview, to show you the problem?

Can you move the tabs around with the keyboard (Shift+Ctrl and Page Up and Shift+Ctrl and Page Down)?

Try to open a new window to see if that works.

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) to see if that helps.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

Hi cor-el, Shift+Ctrl and Page Up and Shift+Ctrl and Page Down - works, but the problem is that I cann't move the tabs to an other position. For example I've got 4 taps open, tab 1 / 2 / 3 / 4. Now I would like to move Tab 2 on position 4 => 1 / 3 / 4 / 2. And this don't work. I cann't move anything.

I'm not sure if I understand your above reply correctly.

"Shift + Ctrl + Page Up" should move the currently selected tab one position to the right.

If the tab bar has focus and you see a focus ring around that tab text then you can move the tab around with Ctrl + Left/Right and Ctrl + Home/End moves the tab to the first/last position.

You can press Ctrl+L (Mac: Cmd+L) to set focus to the location bar and press Shift+Tab if the tabs are on top or the Tab key if the tabs are on bottom until the Tab bar gets focus and shows a focus ring.

Does that work?

"Shift + Ctrl + Page Up" should move the currently selected tab one position to the right. - THIS WORKS!

But 2 month ago, this works with my computer mouse, too. And now I can only switch the taps by keyboard ...

If it doesn't work with the mouse then it is probably a problem with the mouse driver or an extension.

Did you try Firefox Safe Mode or disable hardware acceleration in Firefox.

I've try Firefox Safe Mode + reinstall the maouse driver, but I've got the same result. But it's ok for the moment, I will use the keyboard combination that's ok, too. Thanks for your help. ;)