Hello,

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Thank you!

Is the Firefox window currently maximized?

If that is the case and you want to keep the maximized setting the try to set the browser.tabs.drawInTitlebar pref to false on the about:config page.

• http://kb.mozillazine.org/about:config

The top bar is how it looks when it happens, the bottom bar is how it normally looks.

Also Cor-el, I tried changing the setting as you suggested, then restarted firefox and it happened again after a few minutes though thanks for the response.

Sometimes inexplicable graphical glitches are the result of graphics driver incompatibilities. You can minimize these issues by disabling Firefox's use of hardware graphics acceleration.

You usually need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

orange Firefox button (or Tools menu) > Options > Advanced

On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"

If you restart Firefox, is the issue resolved (or at least improved)?

You have the menu bar visible instead of the Firefox menu button and in that case what I posted above doesn't apply.

If Safe Mode didn't help then try to disable transparency in Windows.
Right click in a free space on your desktop.
Left click on Personalization.
There are four options at the bottom of the screen, choose "Window Color and Appearance".
Select a border color
Uncheck: "Enable transparency"

cor-el I have tried that changing that setting after finding a similar post, but it doesn't solve the issue. In my screenshot, the bottom bar is how it looks normally. The top bar will just happen suddenly with no changing of any settings. It usually happens when I open another tab. After a while it sometimes fixes itself and goes back to normal, otherwise I have to restart firefox. I would rather find a way to keep my settings and stop this happening than disable transparency as I find it terrible to look at, but thanks for your input.

jscher2000 I have followed your advice, but I won't know if it has worked immediately as the problem is sporadic. I will get back to you after I've tested it for a while.