You need to post here for MSE issues:
http://social.answers.microsoft.com/Forums/en-US/category/mseHowever, this error has many causes. If you have or had OneCare, parts of OneCare may still be on the PC. Use the cleanup tool first.
http://social.microsoft.com/forums/en-US/onecareinstallandactivate/thread/399071e2-49dc-4767-932d-d261e3965943/
If the MSE install still fails, see this post for steps to try and how to contact MSE support.
http://social.answers.microsoft.com/Forums/en-US/msestart/thread/908fad3e-f9fc-4d8a-be83-ae7d3bc48db5If you want to reinstall OneCare, the cleanup tool is probably going to resolve your error there, too.
If not, OneCare support:
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator
