It is evidently caused by the Zone Alarm anti-keylogger. One user fixed the issue by updating Zone Alarm.

https://support.mozilla.org/en-US/questions/1420073#answer-1594933

Terry,

Great Call. I've had this problem on different computers a few times, but generally a reboot did the job.

Shutting down my Zone Alarm anti-keylogger did the trick, but just updating Zone Alarm Extreme Security did not solve the problem. Also, I had to eliminate ZA from the start folder and still end task the second ZA anti-key logger in task manager to get the multiple versions of ZA anti-key to stop running. I will give the update route another try as I would like to continue running ZA. I'll update tomorrow.

Thanks for the expertise. It is very much appreciated.

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution.

Thank you for contacting Mozilla Support.

I have the same problem. I have disabled Zone Alarm, and turned off keylogger, but problem still exists . (I am using the virtual keyboard to type this) How do I get and install another version of Zone Alarm?

Turned off the anti-keylogger in ZAES, Zone Alarm Extreme Security,(open ZA window, select Web and privacy, turn off anti-Keylogger so button displays "OFF") and rebooted Firefox. This solved the typing character problem. First tried just disabling ZAES that did not work until I opened Task Manager and did an "end task" on anti-keylogger app that was still running. normally 2 anti-keylogger apps were running. Ctrl+Alt+Delete, select "Task Manager" select Anti-keylogger, left click and select "end task."

Now that I can type, how do I restore the Anti-keylogger function? Solving the typing issue and creating a new problem may be a partial solution, but leaves a new vulnerability to the security system. I have posted this problem to the Zone Alarm help and will post further info if it becomes available.

Hi

Thank you for your patience while we have been looking into this issue. We have issued an update to Firefox that is expected to fix this problem. Please make sure that you have version 116.0.2 of Firefox installed on your device.

For help updating, please see: https://support.mozilla.org/en-US/kb/update-firefox-latest-release#

Thank you.

My update to Firefox Browser is currently 116.0.3. this update has solved the problem. Version 116.0.2 did not solve the problem. Tried again with 116.0.3 and all is well.

Thanks for the upgrade to Firefox. Solved the keystoke problem and allows Zone Alarm's Anti-Keylogger to be installed and operate in the "ON' Status.