I have 3 machines in a rack at the corporate office which I control via Remote Desktop Connections.
One of these machines will 'self-lock' ... as if the user typed ctrl-alt-del - and clicked the 'lock' button.
This happens randomly - sometimes while I am actively using that machine.
The other two machines never do this.
I've compared the client-side connection properties - and they all match - including the user credentials. If there are 'host' side properties that are adjustable, I've not been able to find them.
I've checked/compared screen saver settings (NONE).
I've checked/compared power settings - they all seem to match. One of the two that this never happens on - doesn't have a drop-down box for when to go to standby - but on the other two, this setting is 'Never'.