Okay,
I disabled secure start in UEFI. After that i was able to disable DEP completly with that tutorial:
http://www.thewindowsclub.com/disabl...ion-prevention
I completly disabled UAC
in folder options, I disabled thumbnails and this popup thing for all folders (including desktop).
I disabled all shell extensions of third party software (the pink entrys in ShellExView). Or do you think about of any other shell extension?
After all, I rebooted again and tried again. No difference. It crash on desktop and D:\Sonstiges. It only works in safe mode.