Ever have the problem of Firefox’s main browser window being a little messed up looking? What I am speaking of exactly is a large gray bar along the bottom, wish some red text in it. I have not run into this problem in a long time, but I know others have – so wanted to cover it and how to fix it.
First thing you should do is follow the common Firefox troubleshooting tips:
Check for Faulty Add-ons
Next, take a look at your extensions. It could be that one of your add-ons you have installed has a problem with it. First thing I want you to do when checking out your add-ons is to go to Tools > Add-ons and then click on the “Find Updates” button. See if updating any of your add-ons might help get rid of the issue.
The next suggestion would be to go to Tools > Add-ons, disable all the add-ons you have installed, and then restart Firefox. If the problem has gone away after that, you can then enable add-ons until the problem comes back. This should help you figure out which add-on is at fault. It could also be caused by a combination of add-ons, that do not play nice together, so do not rule that out as a possibility too.
Could it be Spyware/Malware?
This suggestion from mozillaZine might also be worth checking into:
If the problem is in Firefox on Windows, check for a file named m3ffxtbr.manifest in the “chrome” folder of your installation directory (usually “C:\Program Files\Mozilla Firefox\chrome\m3ffxtbr.manifest”). If the file exists, delete it, then restart Firefox. This file is created by the “MyWebSearch Toolbar” (a form of spyware).
Be sure to check out this knowledge base post for more tips on working with this nasty problem. Now the last and nuclear step would be to do a fresh or clean install of Firefox to see if you can get rid of the problem that way. It is a drastic step, but has worked for me in the past.