An error number and more information about your system would be helpful. :-)
See this post for the KB article to troubleshoot install problems -
http://social.microsoft.com/forums/en-US/onecareinstallandactivate/thread/ba26b781-da18-4ce4-be8c-22647bd5d8fc/
How to reach support (FAQ) -
http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
Also, if this is a new install and you do not have a subscription already, you cannot activate a new subscription any longer.
See this post:
http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/0000c782-ed1b-4ed3-8afb-87989bb9638c
Installation of Windows Live OneCare in Windows 7 is not supported. You can use the free Microsoft Security essentials for malware protection -
http://www.microsoft.com/security_essentials/resources.aspx
-steve
~ Microsoft MVP Windows Live ~ Windows Live OneCare| Live Mesh|MS Security Essentials Forums Moderator ~
