I think I would start here:
See this post for the KB article to troubleshoot install problems - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=1588602&SiteID=2
I'd also look at the settings in Internet Explorer for your connection. Go to Tools/Options/Connections/LAN and make sure that automatically detect is not set.
If you continue to have problems, and can't get through to support, send me an email at sboots@mvps.org with a subject line including "OneCare" (to get past my spam filtering) and in the message body, tell me what country you are in, your forum nickname, and paste this link: http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=3532069&SiteID=2. I am not online 24x7, so you may be waiting for a reply, but I'll do my best to hook you up with support.
-steve