Does that "x64" mean you are running 64-bit LabVIEW, or that you are running it on a 64-bit Windows OS?
I ran your code on my Win 7 64-bit and it ran fine. It gave error 116. Which makes sense because you are trying to unflatten the "hello world" string. Why are you trying to do that? It can't unflatten it because it doesn't have the proper bytes prepended to it that tell the length of the string. It things the length of the string is the ascii values of "hell" which is 6865 6c6c in hex. Or 1,751,477,356 bytes and the remaining part of your string is nowhere near that long.