The updater wasn't able to update all the files and some were left as older versions.
Do a clean reinstall.

Download a fresh Firefox copy and save the file to the desktop.

• Firefox 6.0.x: http://www.mozilla.com/en-US/firefox/all.html

• Uninstall your current Firefox version.
• Do not remove personal data when you uninstall the current version.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.

Your bookmarks and other profile data are stored elsewhere in the Firefox Profile Folder and won't be affected by a reinstall, but make sure that you do not select to remove personal data if you uninstall Firefox.

Thanks that solved the problem.

I have downloaded a fresh copy of version 6.0 and saved it to my desktop. I uninstalled 5.0 from my system, however, after uninstalling I did not find any folder named firefox. after uninstall I rebooted my computer and installed 6.0 while in safe mode. I restarted my computer and got the same results as before (i.e Error; Platform version'5.0' is not compatible with minVersion>=6.0 maxVersion<=6.0).

Trying to open FF version 6.0 in safe mode does not work either.

However, if I right click the desktop FF icon and run as administrator it works fine.. and it is version 6.0.

Thanks Bob

I have tried all of the suggestions, also removed every reference to Firefox in the registry, no joy, still comes up with the error, does load if run as administrator, this is not satisfactory though, its ok if I am starting Firefox but no good if it tries to start automatically such as clicking a link in an email.

Therefore until this problem is sorted my default will stay as Chrome!!!!!!!

First of all I must say I use Avast! Pro as anti-virus, and in previous version of FF I set "run always in the sandbox" . After installing FF 6.0 I right click and choose "run always out of sandbox" ... and it works! So it seems it depends from the antivirus settings (in my experience!).

I really don't think that Firefox staff have a clue as to how to fix this problem. I am sure there is a fix for the problem which you can get by paying a fee. I have talked to several Internet marketers who have used FF since it first came out and are now switching to google chrome, opera or even back to the Internet Explorer.

I cannot believe that the only file on my computer that is corrupt is the mozilla Firefox folder. If the folder was corrupt, I would not be able to install an earlier version of FF in that folder.

I am using the opera browser at the present time while replying to this thread.

This problem is marked as solved.

However, the problem still exists for several marketers (17 as of this post).

So how can it be solved?

I have completed a complete system restore to the day that my computer left the factory and I am still getting the same problem.

I have also tried recently to get into live chat at the times stated for each day but no one seems to be there. It is like having a store on main street USA with a sale advertised on sunday and on monday no one opened the store for business.

First of all, all of you who are still having problems, Ask your question in a New Thread. This thread has been marked as Solved therefore you will not be able to receive more Useful replies. When a thread has been marked as Solved, we don't revert to it since we have many more Unsolved & Non-replied threads to look at. I just happened to see this thread, otherwise all of you would have kept idly commenting.

@bculbertson

Make a Backup of your Firefox Profile folder in some other location

• http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

Completely Uninstall Firefox

• https://support.mozilla.com/en-US/kb/Uninstalling%20Firefox
• http://kb.mozillazine.org/Uninstalling_Firefox
• SELECT TO REMOVE USER DATA AND SETTINGS

Download latest Firefox version from one of these links:

• http://www.mozilla.com/en-US/firefox/new/
• http://www.mozilla.com/en-US/firefox/central/
• http://www.mozilla.com/en-US/firefox/fx/
• http://www.mozilla.com/en-US/firefox/all.html

Installing Firefox

• https://support.mozilla.com/en-US/kb/Installing%20Firefox%20on%20Windows
• http://kb.mozillazine.org/Installing_Firefox

Manually Restore the Backed-up Firefox Profile

• http://kb.mozillazine.org/Profile_backup#Manually_restore_the_profile

Check and tell if its working.

Sorry Mozilla folks, Windows 7 fully updated, Zone Alarm Extreme running - still the same error "Error: Platform version '6.0' is not compatible with min version >= 6.0.1 maxVersion <=6.0.1. Any chance you nice folks at Mozillia could look at this issue for us UK folks soon? Cheers 'n Beers Bill

Zone Alarm Extreme is known to protect some files quite aggressively from changes (updates), so you may need to disable that program temporarily to see if that makes things working.