No. I haven't found the original post, but this is similar:
"The file is called overlay.xul and it's in C:/program files/mozilla firefox/extensions under a subfolder with lots of characters as its name. Do a search in the extensions folder and find overlay.xul file."
I deleted the subfolder with lots of characters as suggested by the post I read earlier.
This may not be the solution, but worth a look. It is from this site:
http://www.bleepingcomputer.com/forums/topic223896.html