It is possible that anti-virus software is corrupting downloaded files or is otherwise interfering with downloading files.

Try to disable the real-time (live) scanning of files in your anti-virus software temporarily to see if that makes downloading work.

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

First I disabled the virus program. Then the download thing comes down with the blue bar but it never finishes or actually downloads.

When I attempt to do it a 2nd time I get the corrupt message.

Next I took the .xpi file to the desktop and dragged it to the get add-ons. It gives me that same message that it is corrupt.

When I have the get add-ons window up, there is a thing there that keeps wirling saying loading. Not sure if that's supposed to be like that but I would not think so.

Next I deleted 3 extensions in the ff profile. This did not work either.

I put about:config in the address bar and did a search for xpinstall.enabled This does not come up in the list at all.

Here is what I can tell you farther - I had a computer issue with a script message that kept causing me problems when I was in my gmail accounts. Previous to this I had updated adobe flash. Because I could not get rid of the problem, I did a system restore for one month back.

After it did this restore, I lost Firebug.

What to try next?

Did you try to install the extension directly from the Add-ons website?

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test to see if that helps.

I tried to install directly from add-on website. Still will not work. It seems as though something is blocking them.

I will provide a screenshot of FF profile. Firebug is in there.

I just did the "reset to default" for Firefox and this fixed my issue. I was then able to download Firebug.

Thanks for all your help