Posted 25 July 2007 - 02:50 AM
I just dealt with this problem. I kinda had to piece together some info from different sources to figure it out, so I decided to make a post in case anyone else encountered this and decided to search for an answer.
It's evidently possible for certain things to trigger a large (1"-2") box the color of your window and blank except for a single small carat on the left to appear at the bottom of the Firefox browser. I know now that it's probably linked to an extension.
So, if you have this problem, click on Tools-->Add-Ons in 2.0 (Tools-->Extensions... in 1.5) and make sure you're looking at Extensions. Now, disable all your extensions and restart Firefox. The box shouldn't be there anymore.
Now, turn on the extensions one by one, restarting Firefox each time. When the box comes back, you know you've found your culprit. Uninstall that extension, then reinstall it from the Firefox extension website. If the box is still there, you might just have to do without that add-on.