Do you ever get the error after a fresh reboot of the computer?
Yes, about every second boot. This morning it happened, now in the evening I can throw anything in without issues. Yesterday it happened both in the morning and evening with the same settings as today. When the error happens, almost any starting program can trigger it including browsers, Skype, Notepad, everything, each one usually only once. I always shut my computer down when being away, usually checking my mail and the forums in the morning and having some more activity in the evening. Sleep and Hibernation are disabled.
I took a look at Windows logs and there's a dozen of Error Reporting 1001 LiveKernelEvent notifications featuring the exactly same time stamp. The Action Center has an error report for the times when there's been the "Stopped and recovered" notification popup, matching one of the log time stamps. So not all log entries create an error report. This might be because of the TdrDelay registry entry I created, letting the system recover before a report is triggered.
What annoys me most is this randomness. Every time I make a change, the system works flawlessly for the rest of the session, or even the whole evening including occasional reboots. Then it hits with every single starting program. Aargh!