Please try the following:
Reboot the PC. The run the Firewall repair tool - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2468376&SiteID=2
And also the Virus and Spyware repair tool - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2667445&SiteID=2
Reboot after the tool as completed.
Then, open OneCare and click on check for updates.
If this still doesn't resolve it, please contact support for help -
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
*or*
Uninstall OneCare - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=663806&SiteID=2
Download and run the cleanup tool - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=828910&SiteID=2
And then install OneCare from http://onecare.live.com and activate with the same LiveID used to originally subscribe.
-steve