Hi, I've read various posts about locking macs and the best way seems to be to put the display to sleep and activate the option to require a password upon waking the display up, thus taking the user Lion's 'Lock Screen'. However, this lock screen times out after 30 seconds and the display goes back to sleep. Is there a way to prevent this? Or at least change the duration that the lock screen remains active before the display sleeps again? Thanks.