Thanks for your idea! That's why I originally assumed POSReady updates were mandatory for running Thorium. Maybe, there is really an POSReady update which is urgently needed to run Thorium on my hardware. But I should mention that there are 365 updates in my archive applied after the POSReady hack. And without this hack, you can't install those updates, either. So, it does not make sense to investigate them. And I already have a perfectly working Windows XP Professional installation with all POSReady updates. All my very deep investigations lead me to modify my null hypothesis:
Here is my modified null hypothesis H0: "Thorium crashes due to the lack of one or more POSReady updates under certain hardware conditions". Personally, I tend to accept H0 due to my experiences and deep investigations. Unfortunately, the probability of type II error for this decision cannot be determined again due to the too small sample size, either.