This could be caused by Terminal Services failing to start. To check this open the Services Console ( Start>Run, type "services.msc" without the quotes in the Run box) scroll down to Terminal Services and verify it is started. If Terminal Services is not started double click Terminal Services and start the service and set the startup type to "Automatic" in the drop down menu. Exit the Services Console. If this does not resolve the issue please contact support. How to reach support -
http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
Jim