Do a thorough scan for viruses and malware. Download and run A-squared click here. If that doesn't find anything, click Start - run. Type in msconfig and click OK. In the window that opens click on the "Services" tab. Tick in the box to Hide all Microsoft Services, and then Disable All. OK to close the box, and restart your computer. As you will have disabled your antivirus, don't connect to the Internet. If Outlook Express no longer pops up you will know one of the disabled services was to blame and you can start trying to isolate the culprit.