ScreenSaveTimeOut is reset by some process, so my changes are not preserved. how do I find a process that does it?

"It's quite likely that the value is being reset by the group policy set by your IT department, so the changes you make via the UI or registry are being overwritten next time the policy refreshes.

I'd talk to your IT department and explain the problem. They might exempt your machine from this part of the policy (however, I don't know how easy this would be)."