go to Help Menu -> select "Restart with Add-ons Disabled"

Firefox will close then it will open up with just basic Firefox. You can enable the Add-ons later. Check and tell if its working.

Thanks mha007

Unfortunately it is still giving me the same message

URGENT! Your version of Firefox is no longer protected against online attacks. Get the upgrade - it’s fast and free!

Firefox 3.5.x versions are no longer supported and using those versions may make your system vulnerable; you are using version 3.5.5

The only currently supported Firefox versions are 3.6.18 and 5.0. Firefox 3.6.18 only has 2-3 more months of support and it will be dropped. Firefox 6 will be released in a couple of months.

IMPORTANT: I notice that you may have McAfee installed. Their toolbar may not work with Firefox 5, but they are working on a fix that should be released soon. Check with the McAfee site or McAfee forums for more information on that.

Download the installer and save to your Desktop so that you can find it. When the download is complete, close Firefox (File > Exit), click/double-click on the installer you saved to your desktop and follow the installation prompts.

• Download Firefox 5.0: http://www.mozilla.com/en-US/firefox/all.html
• Download Firefox 3.6.18: http://www.mozilla.com/en-US/firefox/all-older.html

You need to update the following. The Plugin version(s) shown below was/were submitted with your question and is/are out of date. You should update to avoid known security issues with the version(s) you have installed. Click on "More system info..." to the right of your question to see what was included with your question.

• Adobe PDF Plug-In For Firefox and Netscape "9.3.4"
• Shockwave Flash 10.2 r152
• Next Generation Java Plug-in 1.6.0_24 for Mozilla browsers

1. Check your plugin versions on either of the following links':
   • http://www.mozilla.com/en-US/plugincheck/
   • https://www-trunk.stage.mozilla.com/en-US/plugincheck/
   • Note: plugin check page does not have information on all plugin versions
   • There are plugin specific testing links available from this page:
     • http://kb.mozillazine.org/Testing_plugins
2. Update Adobe Reader (PDF plugin):
   • From within your existing Adobe Reader (if you have it already installed):
     • Open the Adobe Reader program from your Programs list
     • Click Help > Check for Updates
     • Follow the prompts for updating
     • If this method works for you, skip the "Download complete installer" section below and proceed to "After the installation" below
   • Download complete installer (if you do NOT have Adobe Reader installed):
     • SAVE the installer to your hard drive (save to your Desktop so that you can find it after the download). Exit/Close Firefox. Run the installer you just downloaded.
     • Use either of the links below:
       • https://support.mozilla.com/en-US/kb/Using+the+Adobe+Reader+plugin+with+Firefox (click on "Installing and updating Adobe Reader")
       • Also see Download link': http://get.adobe.com/reader/otherversions/
   • After the installation, start Firefox and check your version again.
3. Update the Flash plugin to the latest version.
   • Download and SAVE to your Desktop so you can find the installer later
   • If you do not have the current version, click on the "Player Download Center" link on the "Download and information" or "Download Manual installers" below
   • After download is complete, exit Firefox
   • Click on the installer you just downloaded and install
     • Windows 7 and Vista: may need to right-click the installer and choose "Run as Administrator"
   • Start Firefox and check your version again or test the installation by going back to the download link below
   • Download and information: http://www.adobe.com/software/flash/about/
     • Use Firefox to go to the above site to update the Firefox plugin (will also install plugin for most other browsers; except IE)
     • Use IE to go to the above site to update the IE ActiveX
   • Download Manual installers.
     • http://kb2.adobe.com/cps/191/tn_19166.html#main_ManualInstaller
     • Note separate links for:
       • Plugin for Firefox and most other browsers
       • ActiveX for IE
4. Update the Java plugin to the latest version.
   • Download site: http://www.oracle.com/technetwork/java/javase/downloads/index.html (Java Platform: Download JRE)
     • Be sure to un-check the Yahoo Toolbar option during the install if you do not want it installed.
   • Also see "Manual Update" in this article to update from the Java Control Panel in Windows Control Panel: http://support.mozilla.com/en-US/kb/Using+the+Java+plugin+with+Firefox#Updates
   • Removing old versions (if needed): http://www.java.com/en/download/faq/remove_olderversions.xml
   • Remove multiple Java Console extensions (if needed): http://kb.mozillazine.org/Firefox_:_FAQs_:_Install_Java#Multiple_Java_Console_extensions
   • Java Test: http://www.java.com/en/download/help/testvm.xml

Uninstall Firefox. Search Firefox in your Windows drive (C:\) and DELETE all Firefox folders found in the search.

content that was here was deleted at this users request, by a Moderator

Now Restart your computer and re-download Firefox from

http://www.mozilla.com/en-US/firefox/fx/

Check and tell if its working.

DO NOT mess with regedit if you do not know what you are doing. One mistake in editing the registry and your computer may no longer operate or boot up.

mha007:

Please refrain from suggesting editing the registry if you do not know the knowledge/experience level of the poster!

PLUS. editing the registry in this case is not necessary!

i suggested this earlier to some users and it solved their problems which couldn't be resolved by trying various other solutions.

Then, if you suggest a registry edit to someone and they make a mistake and disable their operating system, you will be responsible (financially) for having their system restored?

EDIT: In addition, one mistake and one resulting complaint due to such a drastic measure, could affect the credibility of this forum and all of the contributors attempted to assist users! Think about it!

Editing Registry should be the very last resource. There are numerous articles on line to tell computer users DO NOT mess with Registries unless you are an advanced computer user. Personally, I will never do it especially with problems involving Firefox. I would suggest K_Vella scan his computer for spywares/malwares first to see if that helps.

As you wish. You can ask the Administrators or Moderators to Delete my posts regarding Registry Editor.

In the end the real reason could be in the useragent is set to the old version of Firefox 3.5.5 even though you may be using Firefox 5.0

https://support.mozilla.com/en-US/kb/new?title=Web+sites+or+add-ons+incorrectly+report+incompatible+browser

ufff i give up... i have tried and followed your suggestions but still having issues.. when I click on Help - About Firefox it says I've updated to Firefox 5 however still have same error message upon opening firefox

is there a way for me to copy my bookmarks to explorer?

thank you!

See this posts

https://support.mozilla.com/en-US/questions/851611

Check and tell if its working.