When I open the Tor Browser Bundle I get an error message from Firefox: "Cannot load XPCOM". How can I start the Tor Browser?
Answer #1: This error message is discussed as #10789 in Tor's trac. Users who report this message have a Webroot product installed. This software blocks several DLL files. After Webroot was uninstalled Tor Browser worked without any problems on those users.
If you have webroot antivirus, go to ---|--- IDENTITY PROTECTION ---|--- Application Protection ---|--- and allow
Under Application Protection, allow anything that Webroot has listed that is from your Tor Browser Folder.
Answer #2: this same issue came up much more recently, with users running "Windows 10 preview build 14251". See Tor ticket 18171 for details. Moving to a newer version of Windows 10 preview will resolve the problem.
I had this same problem. At first I thought I had to delete Chrome or Firefox, but that was not the problem. The problem was that my webroot security software was preventing tor from opening.
YOU DON'T HAVE TO DELETE YOUR WEBROOT SECURITY. Here is what you do:
Click on "Identity Protection"
Click on "Application Protection"
Find the file that has the word "tor" in it. For example mine says, "firefox.exe in c:\users\desktop\torbrowser\browser"
Then look to the right and you will see the following options: protect, allow, deny.
This will fix this problem. Hope this helps you.