Double Windows when clicking a link in a message

[Julio]

I tried to get help on my problem directly, through MS
tech support, but apparently I've exceeded the Email
support threshold. Here is my problem:

Every time I click a URL in Outlook my browser pops up two
windows and loads the same URL into both. This happened
when I switched the default browser to FireFox, but
switching back to IE does not resolve the problem.

The first time I clicked a URL in an Outlook message after
switching browsers I got a dialog window that said
something about not being able to find an appropriate
application to open the URL and gave me the opportunity to
select the application, which I did.

While I was working with the dialog window, however, I
didn't notice that Outlook also started Firefox and loaded
the URL. (It was obscured by the dialog window.) Anyway,
I continued working with the dialog window and pointed it
to the Firefox application. At this time the second
Firefox window popped up and loaded the URL.

Now, every time I click a URL in an Outlook message, two
browser windows pop up and load the same URL. Switching
the default browser back to IE does not resolve this
problem.

Any suggestions?

Thanks for your help!
--Julio