I cannot install Firefox extensions

[Flash]

Sorry, I guess I need to read more carefully.

Brian, did you know you don't need the Firefox dotpup? You can download the latest version of Firefox from http://www.mozilla.com/
and there is no "installation" required to run it. All you have to do is click on the gear icon in the Firefox directory. You can drag the gear icon to the desktop, then change it to the Firefox icon, which is provided in the icon directory within the Firefox directory, if I remember correctly.

[Kal]

Move your .mozilla to another folder in /root and start again.
Luck, Kal

[Brian C]

I finally got it! In a tab, I entered "about:config" then did a filter on 'install'. There was a boolean option called 'xipinstall'. I double-clicked it to be 'true', and now I'm all set! Thanks for helping me out!