I am having the same problem on my Y510. Screen Saver is not working at all - never did. The Real Time Monitor does not kick in - never did.
All this on a machine only 2 days old. I have to manually send it off to hibernate.
Any other ideas than what has been posted? I have tried to disable the screen saver settings in Vista, just in case that there is a conflict with Real Time Monitor and vice versa. I dont want to go down the track of disabling Verifcace in safe mode as I find that feature very useful. I do not want to load new drivers unless someone has a URL for that and found that it does cure the problem.