The 0019 error indicates the firewall component of One Care did not install correctly. See this Microsoft Knowledge Base article to resolve the installation error -
http://support.microsoft.com/kb/930159/en-us If you are unable to resolve the installation error please contact support. How to reach support -
http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
Jim - MVP Windows Live - Forum Moderator - Live One Care - Live Mesh