A plugin needed to display page

[GoogleCodeExporter]

What steps will reproduce the problem?
1. left click on icon to switch rendering
2.
3.

What is the expected output? What do you see instead?
Insted of the page in IE I get:
a blank page with a grey block in upper left hand side with "A plugin is needed 
to display page"

What version of the product are you using? On what operating system?
4.0.20130422  Windows 7 Pro 64bit

Please provide any additional information below.

Original issue reported on code.google.com by david.ha...@gmail.com on 12 Sep 2013 at 1:59

[GoogleCodeExporter]

I decided to try and disable all my add-ons then re-introduce them one by one 
to see if there was a conflict. Surprisingly IEtab worked when the only add-on, 
and continued to work as I slowly enabled all the others. So no problem now, 
IETab works perfectly! 

Original comment by david.ha...@gmail.com on 12 Sep 2013 at 2:11

[GoogleCodeExporter]

Okay, after doing a bit of digging in the MozillaZine forums, I found the 
solution.

Disable the add-on, restart Firefox, then reenable the add-on.

It fixed the problem right away.

Original comment by gfin...@gmail.com on 19 Sep 2013 at 4:15