The most common reason for this problem is that the PC date and time are incorrect. Right click the clock in the system tray and select set date and time. Check all parts of the date/time and make corrections, if needed. Reboot if you changed it more than a small adjustment in time. If the OneCare red status and less than helpful message persists, please contact support.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve