Unfortunately, this has been reported by a number of people following the update and the developers are investigating the causes.
This thread may contain an answer for you, though, if you have peer to peer services running under networking.
http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2493861&SiteID=2
If not, please contact support for help:
How to reach support - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
If it fails to validate your subscription, select the option that you are using a trial or beta copy and you can proceed to email support without validation once you've signed in.
-steve