Also: It works in every other program, I can right click and open menus normally.

Did you open and close the browser during that time, or was it opened the whole time?

it was open

You said this is after about 6 hours. Were you surfing the whole time or letting Firefox sit idol?

FredMcD said

You said this is after about 6 hours. Were you surfing the whole time or letting Firefox sit idol?

Hi Fred, I'm having this exact same problem and have for months and am hoping you may be able to help me! It started for me around the same time - 4ish months ago - but I couldn't tell you the version number I was on at the time. I'm having the exact same issue on two different physical computers both running Windows 7 Pro x64, while I do not have this issue on my work computer running Windows 10 Pro x64.

The Problem:

After a period of time, sometimes 6-8 hours, sometimes 48 hours, I am no longer given any context menu's when I right-click in FireFox, either on a webpage or on the toolbar areas. This can happen when leaving FireFox open and inactive over night, then seeing the problem in the morning, or some mornings it works fine and continues to throughout the day, but then stops the following day. So, for example, I am unable to Pin, Unpin or Close tabs completely. Also, when I click on the Menu or Bookmarks button, nothing pops down. The button changes colors to a darker shade like it down when it is depressed but not menu appears. This happens in drop-down menu's on websites as well - they do not appear. I am able to use the up and down arrows, or letter keys, to move around them but the drop-down is gone. This is all fixed if I close FireFox and re-open it. Seemingly like a timer is reset, everything works again for a while.

What I've done:

I started with simple things like unpinning my tabs, closing tabs and removing extensions but non of that worked. I then backed up and deleted my entire Firefox profile under AppData - Local but it started happening on my new profile also. Earlier this week I completely uninstalled FireFox and the update service, and deleted everything Mozilla from all three AppData folders as well as ProgramData. I rebooted and then re-installed FireFox using Ninite. I did not import any data, pin any tabs, install any add-ons or save any passwords. I was trying to be as vanilla as possible, but the problem was happening again the next morning. As of today I just started FireFox in Safe Mode and will see if the same thing happens running in Safe Mode. This effort so far has been concentrated on one of my two machines experiencing this problem, as I was hoping to solve it on one and then apply the solution to the other, but I am at a loss. I can't imagine that additional Windows programs would cause this but there are a few overlapping programs between the two. I have Microsoft Security Essentials and MalwareBytes Premium installed on this primary machine having the issues, whereas I do not have MalwareBytes installed on the other machine also having this issue. I thought the Web Protection may be interfering but I don't believe so now. One other similarity is that both computers are non-domain and the primary account used on both is a non-admin account purposely (I try not to run as admin unless absolutely necessary, for obvious reasons). I'm wondering if possibly not running as an admin is causing an issue somehow? I will try temporarily making myself an admin the next time I experience the problem (assuming tomorrow morning as that's pretty common) to see if that has any positive effect.

Other than that, would you have any ideas or things I may be able to try? I'm open to anything at this point, I just want this fixed! I don't want to move to Chrome. :(

The normal first thing to do is run Firefox in Safe Mode to see if the problem is within Firefox. But the time element makes this impractical.

It would be best to start your own question and let us look at your system details.

After creating the question, please post its weblink here.

Please go to the top of any support.mozilla.org web page and use the Ask A Question link; https://support.mozilla.org/en-US/questions/new Select the product for what the problem is (Firefox or whatever).

Now select the category for the problem. At the bottom is Other.

Describe the problem in brief (one line). Then press <enter>. The website will display any prior posts that might help you. If nothing on the list can help, at the bottom press the button; None Of These Solve My Problem.

Now enter all the relative information on the problem. At the bottom of this, you can Add Images.

Under this is Troubleshooting Information. Please press the Share Data button. This will let us look at your system details. No Personal Information Is Collected.

FredMcD said

The normal first thing to do is run Firefox in Safe Mode to see if the problem is within Firefox. But the time element makes this impractical. It would be best to start your own question and let us look at your system details. After creating the question, please post its weblink here.

Thanks Fred! I went ahead and created my own question here:

https://support.mozilla.org/en-US/questions/1210550

Also it's worth nothing that the issue did repeat itself last night even while Firefox was in Safe Mode. I am going to temporarily promote my user to an Admin tonight and leave Firefox open and idle to see if that has any effect too.