Problem using a URL link from documents.

When clicking a URL link in an email in Outlook or Word, the content appears
in the browser (Firefox 2) BUT an installation program always launches
(Winter Dream Screensaver) as well.
Removing the latter application and deleting any remaining files does not
resolve.

This effect does not occur if IE7 is made the default browser.

If Firefox is started by a shortcut with the same URL and other arguments,
then it works correctly.

I have run both Spybot and AVG Anti-spyware, plus Windows Defender.
--
Jon