If you are installing on Windows XP see this Microsoft Knowledge Base article to resolve the 0020 error -
http://support.microsoft.com/kb/930162 If you are installing on Vista try running the install cleanup tool -
http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/399071e2-49dc-4767-932d-d261e3965943 then try to install One Care. If the installation fails again with the 0020 error please contact support. How to reach support -
http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
Jim
Microsoft MVP Consumer Security - Forum Moderator - Live One Care - Live Mesh - Microsoft Security Essentials