Which horizontal bar do you mean?

Do you mean the scroll bar or a toolbar like the Add-ons Bar (View > Toolbars > Addo-ons Bar; Ctrl+/)?

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot and make sure that you do not exceed the maximum file size (1 MB).

I mean the scroll bar.

Now, somehow the horizontal scroll bar started to work again. It was after I checked plugins and Firefox disabled my old java version. Is it something to affect this behaviour?

I hope it will not happen again. Thank you for your reply.

You're welcome.

Was the scroll bar disabled (dimmed) or did it appear normally, but didn't work?

the scroll bar was in place as usual, but I was not able to move it to the right as I needed to. That's what I mean by "frozen". In fact it didn't work.

Once again the horizontal scroll bar is not working. This time I will add an image but it will not help too much as I don't know what kind of information you may need to debug the issue. Please let me know.

Looks like a problem with detecting the current width of the browser window.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

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

If the above didn't help then check for problems with the localstore.rdf file.

• http://kb.mozillazine.org/Corrupt_localstore.rdf
• https://support.mozilla.org/kb/Toolbar+keeps+resetting

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder