Do a clean (re)install and delete the Firefox program folder (C:\Program Files\Mozilla Firefox\).

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

• Firefox 9.0.x: http://www.mozilla.com/en-US/firefox/all.html

Uninstall your current Firefox version, if possible.

• Do NOT remove personal data when you uninstall the current version or you lose your bookmarks and other data in the profile folder.

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.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

Uninstalled Firefox and deleted folder as described above. Downloaded new 9.0.1 install and ran it. Same result. Same error about missing MOZCRT19.dll. MOZCRT19.dll does reside on my Win7 PC in the Thunderbird directory in Program Files (86). Firefox 9.0.1 has loaded successfully on another Win7 PC, a Vista PC and an iMac in my network.

However, Zone Alarm had its Browser Virtualization option turned on. I turned it off and went through the uninstall/delete directory/ einstall procedure and Firefox loaded and ran as normal. To check this I turned Zone Alarm's Browser Virtualization on again and the missing MOZCRT19.dll popup occurred when I tried to start Firefox. Repeated the uninstall/delete directory/reinstall procedure and Firefox now runs normally as long as Zone Alarm's Browser Virtualization is turned off.

I have Zone Alarm Extreme and this solution worked.

This is the second time I and others have experienced a conflict with Firefox and Zone Alarm's Browser Virtualization option. Mozilla/Firefox and CheckPoint/Zone Alarm need to get together about this and resolve it once and for all. This is becoming annoying. Mozilla/Firefox prides itself on its concern for security yet here is an additional layer of security from CheckPoint/Zone Alarm that can't be used with Firefox.

Same/similar issue (Windows 7, Firefox 9.0.1) using Kaspersky Pure Safe Run Sandbox, virtual environment. Firefox 9 works fine if I am simply initiating it from the Win 7 desktop, however I receive the Firefox MOZCRT19.dll system error when attempting to initiate Firefox from within the Kaspersky secure virtual environment. Disabling add-ons nor reinstalling Firefox resolved anything for me. Before updating to version 9, Firefox was working successfully from within the Kaspersky Sandbox, no errors, no problems with add-ons. Agree with prior comment, would prefer using Firefox within the safe virtual environment if possible. Hope this can be fixed.

Try to ask advice at the Kaspersky forum.

• http://forum.kaspersky.com/

Ran into this problem today, too, but it went away when I cleared virtual data from the Internet > Web Security > Settings page. Now both Firefox and IE browsers are functioning properly with virtualization turned on.

OK, the disable virtualization in Zone alarm and a reload of the new (V13) of firefox worked. Since this problem started in (V9) and we are now in (V13) what comes to my mind is why has it not been fixed by now. Agreeing with some of the above people, I want the full capabilities of browser AND security.

Side note: Somewhere along the line my bookmarks disappeared and now there is a completely new format without my bookmarks. Where are bookmarks stored so maybe I can get them back from one of my backups.

After many attempts to correct this problem--and I mean hours at a time many times, with weeks or months between while I wait for Firefox to do something about the issue--I am fed up and wonder why anyone would use Firefox. I used to love it. It worked so well and hey it wasn't Explorer.

The frustration of trying to deal with the company is even worse. Contact us? Really? A map? yes, I'll travel the world visiting Mozilla offices in hopes of finding MOZCRT19.dll and actually getting the ruddy thing onto my computer.

Make a suggestion? Sure, first download the current version of Firefox. Umm...yes, have been trying for hours, days, weeks to do that. Wanted to mention to you how utterly impossible it is to do that. But before I can mention it, I have to somehow do it. In which case, of course, I wouldn't need to mention it.

What do we need from computer programs? We need them to download and open. If they can't do that, pfft.

Thanks to those who have tried to give solutions.