I'm moving your post to the multi-PC Management topic and out of the Update topic.
There's at least one other thread here with someone reporting that error - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=3028060&SiteID=2. Is there any other text with that and at what point do you encounter it?
I am assuming that it is happening when you log in to provide your subscription LiveID. Check the date and time on your PC, which can cause odd issues when trying to do LiveID related things through OneCare.
In the other thread, I recommended support, but never got any further posts from the person with the problem.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve