I've been having a weird issue with Gmail window formatting for quite a while now and it drives me mad. It only occurs on one of my computers (does not occur on laptop, nor PC at work). It affects all of my Gmail accounts. I use Mozilla Firefox 12.0 and 13.0 (changing between versions does not affect the issue).
Some time ago a weird horizontal bar appeared at the bottom of the screen. Normal mail text area increased in width something like 10000%. So basically, a paragraph became a single line. Only Enter makes the text go into new line.
On both laptop and work PC, there is NO horizontal bar at the bottom of the window. I can only see it on my main PC. Some messages that contain < center > tag are the most annoying, because I have to scroll the horizontal bar to the exact middle position (which in case of short messages is hard).
I've of course done a good bit of googling, but haven't found any working solution.
How to fix this issue?