Windows Vista security features can cause browsers such as Firefox to fail to open web pages when when a link is clicked in another program such as Outlook.
The problem occurs when the browser is launched using the “Run as administrator” option in Windows Vista, which is sometimes used to install plugins.
Hypervisor tests show that when Firefox is used in this mode and the user clicks an HTTP link contained in an Outlook email, rather than the web page opening in Firefox, Outlook will display a “General failure. The URL was:” error message. The problem does not occur when Firefox is run without the “Run as administrator” option.