I recently installed Firefox 3 and made it my default browser. I decided that I liked IE better, so I switched my default browser back to IE. Now, however, if I have IE and Outlook Express open simultaneously, and then click on a link in Outlook Express, a new IE window will open. It used to open a new tab in the existing IE window, which I much prefer. I cannot figure out how to restore the former behaviour. In an attempt to resolve this, I uninstalled Firefox, and upgraded IE from version 7 to version 8 beta, to no avail. It still insists on opening a new window rather than a new tab. How can this be fixed?