Hello,

Try Firefox Safe Mode and see if you can access your options there. 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.

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.

Also, Firefox 34 is out, you can update by going to:

• Help (or > ) > About Firefox

Do you have the Ghostery extension?

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Type about:preferences<Enter> in the address bar.

Does it work?

Thanks to all of you! :)

Indeed Ghostery was installed and the root cause of it. You don't even need to restart Firefox - as soon as Ghostery is active, the preferences windows is blank. about:preferences also works with Ghostery enabled.

So only one question remains: Is this something to be fixed in Ghostery or in Firefox?

For now, disable it if you need to. Also contact the programs help page.