I have WinXP, IE 6 and Outlook Express. Sometimes when I try to send a link, the email will open in Outlook. There will be no Send button because I don't use Outlook. I go to Tools/InternetOptions/Programs/EMail and change it to back to OE. It will work for a few weeks but invariably it changes back to Outlook. Is there some sort of electronic "safety wire" to keep it from slipping back to Outlook? Thanks.

Since you're not using Outlook, you can uninstall it. Go the Control Panel/Add-Remove Programs and then the MS Office installation. Select it and then click the Change/REmove button. Use the Change option and just select Outlook for removal.

Should you ever desire to reinstall Outlook, you can just reverse this process.
I hope this helps.