I can confirm this as well in Linux Mint. It usually happens after extended browsing, reading manga. When this happens again I'll make a moving screen shot of it, to show the unwanted effects. Is there any other information you guys need for this bug?

I have Win XP Pro and also have this problem. I did not have it with the last 3.XX update and for a day did not have the problem with 4.+. I got the issue after the last Windows Security updates (5 I installed today from the last 2 weeks). Maybe it is related in some way.

I should add that when I right click on a link from a website to open in a tab, etc., those menus do not stay up either.

You can start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes/Appearance).

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

The only Addons/Extensions I'm running are Shockwave, Java, and Adblock Plus 1.3.5.

I can confirm this problem on Debian unstable 64bit. I'm using the firefox4-binary (amd64) from the ftp-repository on mozilla.org. I have had this problem since the early betas, which I've been using on Ubuntu 10.04 and 10.10 and it seems to appear regardless of any specific configuration, be it OS, architecture or plugins. The problem usually appears after a few hours of browsing, I couldn't observe any correlation with a specific event.

A workaround that I've found is to minimize/restore the browser window. After that, menus behave as expected (at least for a while).

I have this problem. All the pulldown menus seem to randomly disappear and reappear when mousing over them (bookmarks, menus, recent browse history). I'm able to get things to work by knowing the layout of the pulldown. I.e. I know the top of the link right click menu is "Open in New Tab". So, even if the menu disappears/becomes transparent, I can still use the mouse to click that location and get a response. I tried some of the suggestions in this thread. Disabling all the addons didn't seem to help, but running in safe mode does.

Here is a video of the issue.

http://www.youtube.com/watch?v=sRNscNVY1Nc

I have the same problem. Try this:

Firefox -> Options -> Options -> Advanced Tab -> uncheck "Use hardware acceleration when available"

After doing this my menus draw normally and the browser still seems to run well. I guess we'll have to wait for hardware acceleration once they get the bugs out :)

I have the same problem. However, I thought there might be a correlation between Thunderbird and Firefox. I usually have both open. Well the menu in Thunderbird was disappearing. I closed Firefox and the menu was fine. Later the reverse happened, Firefox menu was disappearing. Closed Thunderbird and menu is fine. Curious isn't it?

I tried NetMagi's solution copied below:

Firefox -> Options -> Options -> uncheck "Use hardware acceleration when available"

and the problem has disappeared.

glad to hear it worked for you as well!

I have the same problem in Ubuntu, but it only seems to happen if I leave Firefox open and the screensaver activates. After that I am unable to use the menus as they disappear as soon as the mouse is moved. If I activate the menu but do not move the mouse, I can select options using the keyboard. Otherwise restarting Firefox fixes the problem.

Unchecking "Use hardware acceleration when available" fixed it immediately for Ubuntu / Firefox 4.0 -- no restart was needed.

In Firefox 4.0 for Ubuntu / Linux, the check-box is at: Edit > Preferences > Advanced > Browsing

Edit: the problem reappeared. Just going to the Edit > Preferences dialog box fixed it. I suspect there is some internal state variable that is reset by initializing ANY dialog box. I'll test this the next time it happens. I think it has nothing to do with hardware acceleration, at least for me -- I've re-enabled it, and the drop-down menus are still working.

Try this:

Open any dialog-box from the menu-bar, using either: 1. ALT-key or CTRL-key combination, or 2. Using the down/up arrow keys, followed by <ENTER> when the desired item is highlighted.

Close the dialog-box.

That fixes it for me temporarily. I was fooled into thinking unchecking "Use hardware acceleration when available", when just opening that box and closing it, without checking or unchecking anything, still does it.

Way too weird...! I'm running two monitors, Win 7. The problem occurs only on one monitor (the home one). When I drag the Firefox window over to the other monitor, the drop-down's work just fine.......!!!!!!!!!!!!!!!!!????????????????????

Update: disabling hardware acceleration DOES make the drop-downs work OK on both monitors....at least for now.

I am having the same problem and then some. I am seeing disappearing menus and jerky mousepointer in other apps as well and on the MS quicklaunch bar. If I shut down FF4 the problem goes away completely.

I AM NOT A TECHIE. I DO NOT KNOW WHAT I AM DOING WITH SOME OF THE TIPS ABOVE AND DO NOT WANT TO SCREW ANYTHING UP. LIVE CHAT IS NEVER OPEN.

COULDN'T SIGN INTO FIREFOX. COULD NOT RESET PASSWORD. HAD TO RE-REGISTER WITH ANOTHER E MAIL.

CAN'T USE PULL DOWN MENU'S. CAN'T USE MANY WEB SITES BECAUSE OF THIS.

IF I DO NOT HEAR FROM YOU ALL TODAY I AM GOING BACK TO EXPLORE. 4.0 SUCKS. TOO MANY PROBLEMS

EMILY

I am having this problem with Firefox 7 from Mozilla running on Debian Squeeze under Gnome/Compiz. Minimizing momentarily does fix it, but it continues to go wrong again.

I am having this exact same problem with version 10.0.1 - What is strange is I have a two monitor setup and it works fine on monitor 1 but once I move the firefox window over to monitor 2 it has the issue.