Try disabling User Account Control: Control Panel>User Accounts>User Accounts>Turn User Account Control On or Off>Uncheck it>Click Ok>Restart.
(from here: http://www.mydigitallife.info/2006/12/19/turn-off-or-disable-user-account-control-uac-in-windows-vista/) --~--~---------~--~----~------------~-------~--~----~ http://groups.google.com/group/python_inside_maya -~----------~----~----~----~------~----~------~--~---
