Friday night I ran the online version of nod32. Because it installs an active X component I had to use Internet Explorer. Firefox has been my default browser for years. While running nod32 I was aware something was not quite right because an action that should've opened Firefox opened IE. Afterwards I rebooted and everything seemed to be fine. This morning Firefox will not open. For an instant an icon appears as it normally does while Firefox is loading but it quickly goes away. Using IE I downloaded another copy of Firefox and installed it with the same result. As a test I downloaded Opera and it runs fine. Where should I be been looking for some setting that is interfering with Firefox?