Thanks, but it seems that I could solve this problem meanwhile.
The PC didn't want to start anymore since I disconnected it from the 220 Volt power socket while it was shutdown and off. When I plugged it into the socket again and pressed the start buttom nothing happened, not even the blue power LED was burning.
Then I tried a different 220 V power cable, didn't disconnect it, and the PC was starting again. I'm not sure what the reason was, but in Germany the 220 V plugs and sockets are symmetric, which means that the 220 V AC wire (live) and the neutral wire (we call it Null) could be swapped, if you put the plug into the socket in the opposite direction. I think in other countries this is not possible, like in GB.
Maybe there are small currents from the monitor or from the DSL-modem pumping up the voltage level of the PC while it is off and disconnected from the power line so that this voltage level later prevents it from booting when you press the start button. This is only an assumption. Lets see how long it works now ??
No, I have no PayPal account and I really don't want it, because that are all criminals in my eyes.
But you can make a collection for my funeral, if you like that.
