Since disabling the OneCare firewall allows the program to work, the program file or files are being blocked or the ports it needs are being blocked. If the ports suggested by the developer have been allowed in the advanced firewall settings, and the program is listed as allowed, please contact support for help.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator