00_pe_return_00.asm - not good

[catafest]

Take a look at :
https://stackoverflow.com/questions/11177137/why-do-most-x64-instructions-zero-the-upper-part-of-a-32-bit-register ...
a good default example for me into x64 is:

format PE64 GUI
include "win64ax.inc"

.data 
Caption db 'Win64 assembly program',0 
Message db 'Hello World!',0 

.code 
start: 
xor r9d,r9d 
lea r8,[Caption] 
lea rdx,[Message] 
xor rcx,rcx 
call [MessageBox] 
mov ecx,eax 
invoke ExitProcess,0 
.end start