Outlook Express and Internet Explorer share many files. Perform a repair of Internet Explorer. From Control Panel select Add/Remove Programs. Scroll down to Microsoft Internet Explorer and highlight it. Click on the Add/Remove button. When the IE Tools menu comes up, select Repair. Click OK.
Also, you can get to the IE Tools menu by clicking Start > Run and type
If still no joy, back up your emails / address book ,uninstall and reinstall Outlook Express.