Trillian wont open links in Firefox under Vista

Under Windows Vista, when I’d click any link in Trillian, it would open Internet Explorer to display it.

Firefox was set as my default browser. This setup worked fine for me under Windows XP.

Fix:
Trillian Preferences -> Text Conversations
Uncheck Open links in a new browser window

Solution found here:
http://www.howtogeek.com/