Good news: Memtest went fine and without errors.
Dave, okay, the smily could be an unicode character, but how about the string ¨PlayTime¨ instead of the other string, that is usually there?
But I do agree, I will keep an eye on the partition, and monitor its condition, also the running tasks, config.sys and co.
I might also try out some of the tools, that Andreas has posted.. but that maybe in a virtual machine, to practice the usage of these tools.. : )
Thanks to you all, for your great ideas!! \o/
When there is something new, I will keep you posted here.