It has nothing to do with leveling or extruder hight.Well the problem occures random with almost every print while printing.Yes all my print starts off ok.I tried different models to export with several CAD Design software (Siemens NX,Solid Works,Mastercam).That could not be the problem.
I did some research and I found out when I slice with Simplyfi3D and save the G-code on the external SD card all is fine.In Flashprint the same crashes when I sent the G-code via usb.So when I sent G-code via usb the file would be stored on the internal TF card and I think that is the problem.Maybe a corrupt TF-Card?