This is usually caused by the presence of conflicting software such as other antivirus or antispyware programs. If you have conflicting programs uninstalling them should resolve the issue. If you have no conflicting programs or uninstalling them does not resolve the issue please contact support. How to reach support - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90Jim - MVP Windows Live - Forum Moderator - Live One Care - Live Mesh