Open OneCare and it should tell you if there any issues needing attention that are causing it to be in yellow status. If OneCare is green, but the system tray icon is yellow, try rebooting the PC. If that does not resolve it, please 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 ~