You are using an unsupported beta version of Firefox 3.6. Update Firefox to Firefox 3.6.3 (download it off the official site - getfirefox.com ) and see if that fixes the issue.

As I already mentioned I have tried the Mozilla Firefox version 3.6.3 but I have the same problem in this browser, ever since I installed the beta. Do I have to completely delete the beta from my system for add-ons to work again?

On paper (the majority of the cases), you don't, as long as the beta and the stable builds are installed in different locations.

If this is an issue you've been noticing for a few days (i.e., on different windows sessions) then I don't know how to help. But if you haven't restarted your computer yet, do this:

1 - install an extension; 2 - close the browser (don't click the restart button, just close it); 3 - press CTRL+SHIFT+ESC to open the task manager; 4 - see if Firefox is still running. If it is not, jump to 6; 5 - terminate the firefox.exe process (in the processes tab, not in the applications tab - if you're using Windows' default task manager) 6 - start firefox.

If this doesn't fix the issue, I have no idea how to help you. Sorry. Hopefully someone else will.

I've tried these steps, also removed the Firefox Beta altogether, restarted the computer. Still doesn't work. I suppose worst comes to the worst I'll have to remove Firefox altogether and reinstall it from scratch.

That shouldn't be needed. Do this, please:

- type about:support in your address bar and press enter - click "Copy all to clipboard" - paste here the result (just paste)

That should be helpful, since it's possible that there's some issue with the profile itself, and not the Firefox installation.

EDIT:

To the mods, I accidentally reported this post, never mind. Also, please include some "unreport" function. It's pretty basic...

Delete the files extensions.* (extensions.rdf, extensions.cache, extensions.ini) and compatibility.ini in the Firefox profile folder to reset the extensions registry. See "Corrupt extension files": http://kb.mozillazine.org/Unable_to_install_themes_or_extensions

If you see disabled extensions that are not compatible on the next start in "Tools > Add-ons > Extensions" then click the "Find Updates" button to do a compatibility check.

Thanks, deleting the files worked.

I just updated to 3.6.6 and I have the same issue. No matter how many times I terminate the process and restart firefox, I cannot get it to actually install the addons.

 Application Basics

       Name
       Firefox

       Version
       3.6.6

       Profile Directory

         Open Containing Folder

       Installed Plugins

         about:plugins

       Build Configuration

         about:buildconfig

 Extensions

       Name

       Version

       Enabled

       ID

       Firebug
       1.5.4
       true
       firebug@software.joehewitt.com

       Java Console
       6.0.16
       true
        

       Microsoft .NET Framework Assistant
       1.2.1
       true
       {20a82645-c095-46ed-80e3-08825760534b}

       Adblock Plus
       1.2
       true
        

       WebMail Notifier
       2.4.2
       true
       {37fa1426-b82d-11db-8314-0800200c9a66}

 Modified Preferences

     Name

     Value

       accessibility.typeaheadfind.flashBar
       0

       browser.history_expire_days.mirror
       180

       browser.places.smartBookmarksVersion
       2

       browser.startup.homepage
       http://wowsource.us

       browser.startup.homepage_override.mstone
       rv:1.9.2.6

       extensions.lastAppVersion
       3.6.6

       general.useragent.extra.microsoftdotnet
       ( .NET CLR 3.5.30729; .NET4.0E)

       network.cookie.prefsMigrated
       true

       print.print_printer
       HP Photosmart C7100 series

       print.printer_HP_Photosmart_C7100_series.print_bgcolor
       false

       print.printer_HP_Photosmart_C7100_series.print_bgimages
       false

       print.printer_HP_Photosmart_C7100_series.print_command

       print.printer_HP_Photosmart_C7100_series.print_downloadfonts
       false

       print.printer_HP_Photosmart_C7100_series.print_edge_bottom
       0

       print.printer_HP_Photosmart_C7100_series.print_edge_left
       0

       print.printer_HP_Photosmart_C7100_series.print_edge_right
       0

       print.printer_HP_Photosmart_C7100_series.print_edge_top
       0

       print.printer_HP_Photosmart_C7100_series.print_evenpages
       true

       print.printer_HP_Photosmart_C7100_series.print_footercenter

       print.printer_HP_Photosmart_C7100_series.print_footerleft
       &PT

       print.printer_HP_Photosmart_C7100_series.print_footerright
       &D

       print.printer_HP_Photosmart_C7100_series.print_headercenter

       print.printer_HP_Photosmart_C7100_series.print_headerleft
       &T

       print.printer_HP_Photosmart_C7100_series.print_headerright
       &U

       print.printer_HP_Photosmart_C7100_series.print_in_color
       true

       print.printer_HP_Photosmart_C7100_series.print_margin_bottom
       0.5

       print.printer_HP_Photosmart_C7100_series.print_margin_left
       0.5

       print.printer_HP_Photosmart_C7100_series.print_margin_right
       0.5

       print.printer_HP_Photosmart_C7100_series.print_margin_top
       0.5

       print.printer_HP_Photosmart_C7100_series.print_oddpages
       true

       print.printer_HP_Photosmart_C7100_series.print_orientation
       0

       print.printer_HP_Photosmart_C7100_series.print_pagedelay
       500

       print.printer_HP_Photosmart_C7100_series.print_paper_data
       1

       print.printer_HP_Photosmart_C7100_series.print_paper_height
       11.00

       print.printer_HP_Photosmart_C7100_series.print_paper_size_type
       0

       print.printer_HP_Photosmart_C7100_series.print_paper_size_unit
       0

       print.printer_HP_Photosmart_C7100_series.print_paper_width
       8.50

       print.printer_HP_Photosmart_C7100_series.print_reversed
       false

       print.printer_HP_Photosmart_C7100_series.print_scaling
       1.00

       print.printer_HP_Photosmart_C7100_series.print_shrink_to_fit
       true

       print.printer_HP_Photosmart_C7100_series.print_to_file
       false

       print.printer_HP_Photosmart_C7100_series.print_unwriteable_margin_bottom
       0

       print.printer_HP_Photosmart_C7100_series.print_unwriteable_margin_left
       0

       print.printer_HP_Photosmart_C7100_series.print_unwriteable_margin_right
       0

       print.printer_HP_Photosmart_C7100_series.print_unwriteable_margin_top
       0

       print.printer_Microsoft_XPS_Document_Writer.print_bgcolor
       false

       print.printer_Microsoft_XPS_Document_Writer.print_bgimages
       false

       print.printer_Microsoft_XPS_Document_Writer.print_command

       print.printer_Microsoft_XPS_Document_Writer.print_downloadfonts
       false

       print.printer_Microsoft_XPS_Document_Writer.print_edge_bottom
       0

       print.printer_Microsoft_XPS_Document_Writer.print_edge_left
       0

       print.printer_Microsoft_XPS_Document_Writer.print_edge_right
       0

       print.printer_Microsoft_XPS_Document_Writer.print_edge_top
       0

       print.printer_Microsoft_XPS_Document_Writer.print_evenpages
       true

       print.printer_Microsoft_XPS_Document_Writer.print_footercenter

       print.printer_Microsoft_XPS_Document_Writer.print_footerleft
       &PT

       print.printer_Microsoft_XPS_Document_Writer.print_footerright
       &D

       print.printer_Microsoft_XPS_Document_Writer.print_headercenter

       print.printer_Microsoft_XPS_Document_Writer.print_headerleft
       &T

       print.printer_Microsoft_XPS_Document_Writer.print_headerright
       &U

       print.printer_Microsoft_XPS_Document_Writer.print_in_color
       true

       print.printer_Microsoft_XPS_Document_Writer.print_margin_bottom
       0.5

       print.printer_Microsoft_XPS_Document_Writer.print_margin_left
       0.5

       print.printer_Microsoft_XPS_Document_Writer.print_margin_right
       0.5

       print.printer_Microsoft_XPS_Document_Writer.print_margin_top
       0.5

       print.printer_Microsoft_XPS_Document_Writer.print_oddpages
       true

       print.printer_Microsoft_XPS_Document_Writer.print_orientation
       0

       print.printer_Microsoft_XPS_Document_Writer.print_pagedelay
       500

       print.printer_Microsoft_XPS_Document_Writer.print_paper_data
       1

       print.printer_Microsoft_XPS_Document_Writer.print_paper_height
       11.00

       print.printer_Microsoft_XPS_Document_Writer.print_paper_size_type
       0

       print.printer_Microsoft_XPS_Document_Writer.print_paper_size_unit
       0

       print.printer_Microsoft_XPS_Document_Writer.print_paper_width
       8.50

       print.printer_Microsoft_XPS_Document_Writer.print_reversed
       false

       print.printer_Microsoft_XPS_Document_Writer.print_scaling
       1.00

       print.printer_Microsoft_XPS_Document_Writer.print_shrink_to_fit
       true

       print.printer_Microsoft_XPS_Document_Writer.print_to_file
       false

       print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_bottom
       0

       print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_left
       0

       print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_right
       0

       print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_top
       0

       privacy.sanitize.migrateFx3Prefs
       true

       security.warn_viewing_mixed
       false

It says the addons are enabled but they actually aren't.

Original poster here. Funnily enough I had the same problem as Mike today. I deleted the files as Cor-el suggested and it installed the Add-Ons as normal again.

Yes, thank you Cor-el, that resolved my problem as well and sorry I didn't post back to let you know that. Thanks cor-el! And I'm glad you got your issue resolved too, Liam.