My computer doesn't lock itself or turn off the monitor, I believe, when it wants to be rebooted.
I'm not sure if this really is the actual cause or not but when I notice my computer isn't locking and the monitor isn't shutting off as it supposed too I've been led to believe it is because some updates have been applied and that the computer needs to be rebooted. (I was told this by a Tech Support employee at work.)
UPDATE My computer was still on again this morning and no updates have been installed that I can see.
There is a policy set for my Power Options which locks down the time at which my display turns of, which is 15 minutes, and it also required to provide a password.
I don't really feel comfortable knowing my computer has been sitting at the office unlocked all night and who knows what anyone could have done with it during that time. Not to mention the fact that the monitor could potentially burn in. I've actually already gone through one monitor which had the windows xp lock screen burned in to it, but now this still seems to be a problem on my brand spanking new windows 7 machine.
Besides me being more proactive and remembering to manually power down my machine each night, does anyone have any other advice to prevent this from happening in the future?