[tehmaco]

Windows 7 64 bit here - it just has the error message box, and the same text in the cmd window, it doesn't open the file though :)

"This version of foo.txt is not compatible with the version of Windows you're running. Check your computer's system information to see whether you need a x86 (32-bit) or x64 (64-bit) version of the program, and then contact the software publisher."

[JonathonW]

That's because it's treating it as a 16-bit DOS executable (since it has the 'MZ' magic number but not the rest of the PE header that tells Windows that it's 32 or 64-bit). 64-bit Windows can't run 16-bit executables at all.

32-bit Windows should fail a little later in the execution process; it can run 16-bit software, but your text file is missing the rest of the MZ-format header.