Depending on your OS, you may have an option to "Set Program Access and Defaults". Click the Start button to see if it's there. If not, go to Add/Remove Programs and see if it's on the left hand side. If you find it, click it, and set Internet Explorer as your default web browser, and Outlook Express as your default email program (if previously that was your program). Click OK.
If you can't find it, post back.