Are you trying to use a CD? If so, go to
http://onecare.live.com and install the trial instead as your CD may contain an older installer. Once the trial is installed, open OneCare, click on the Subscribe link, sign in with a LiveID and then select the option to activate with a product key.
If you are encountering other errors during the install, see the following:
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/
And, if you need more help, provide more details on the errors encountered and about your system or contact 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
