[7127] Firefox addon extensions do not work, cannot install xpi's

[anykey]

Hello folks, I have been using Seven since 7000. I now have 7127.
My problem is with Firefox xpi extensions.
I have read in the past that this is a known issue with installing xpi, but do you think I can find it now 

My Firefox addon extensions do not work, nor do they uninstall/reinstall.
What do I need to tweak, please...

[anykey]

I am just wondering if I have posted this in the wrong section 

[phat vapor]

try uninstallimng firefox completely and restarting ur pc then reinstall that should work

[anykey]

You're right. It should. I don't though. 

[phat vapor]

hmmmmmmmmm thats a strange one personaly i would do a format and that should work but thats just me don;t no if u have all ur stuff backed up if u have do a format

[anykey]

Sorry gangsta, I don't do formats. They are the last resort.
I have image backups to fall back on when things go nasty.
So, yeah, stuff is well backed up, thanks 

This however is a fresh, clean, installation of 7127. I am just going through setting up everything.

I know in the back of my mind that I have read about xpi's being an issue with Seven.
At the time I had no problem, now I have. And I cannot find that solution/tweak I saw a couple of weeks ago. Grrhh 

[anykey]

...I am just thinking a bit more about this issue.
Instead of xpi should I be saying I have a problem with Seven and installing  msi.