How do I get rid of the message the requested lookup key was not found in any active activation context in simple terms please

This is a IE7 problem.

Unistall Internet Explorer 7 from:
XP - Control Panel -> Add/Remove
Vista - Control Panel -> Programs and Features
***(Shortcut -> Start - Run, type "appwiz.cpl")

Check the box to "Show Updates"

Remove IE 7 and reinstall it.

Hope this helps...
Grant