Hello,
This is just a guess - but C0H sounds like "C0" in hexadecimal format,
which is equal to 192 in decimal.
Windows error code 192 is defined in Winerror.h as
ERROR_EXE_MARKED_INVALID,
If so, then an EXE file image is damaged or invalid - maybe NTVDM
itself, or the 16-bit EXE...