First, make sure that Firefox is set as the default browser. Ref: [[How to make web links open in Firefox by default]] and [[Setting Firefox as the default browser does not work]]. If links in Outlook Express that should open Firefox freeze the entire computer, you could try temporarily setting Internet Explorer (or another browser) as the default (see http://kb.mozillazine.org/Default_browser#Using_Set_Program_Access_and_Defaults for one way to do that). If clicking links in Outlook Express still freezes the computer, you should seek help in a Windows XP forum or an Outlook Express forum ... for example, I found these with a google search: *http://answers.microsoft.com/en-us/windows/forum/windows_xp-networking/outlook-express-6-causing-computer-to-freeze/75fb3e15-0934-4fb9-888b-3d82d6c7ae10 *http://www.windowsbbs.com/microsoft-mail-outlook-outlook-express-windows-mail/88467-can-not-open-links-e-mail.html