Hi Steven,
With the Live Mesh Remote Desktop enhancements installed, once you choose to hide the remote desktop, mouse and keyboard functionality will be disabled on the host computer, with the exception, as you note, of Ctrl+Alt+Del. Someone at the remote console can use Ctrl+Alt+Del to get to the login screen, though to gain access to the computer that person would need to know your password (assuming you have a password on that computer) or have an account & password of his or her own. The brief flash of the desktop that you see before being sent to the login screen is a known issue that we’re working to resolve.
I hope that helps,
Ben.