As tux said, GP4 Master does not support patch version (9.6) either the original exe or the decripted--or as you said, cracked--exe. Don't waste your time with pacthed exe. To do the trick, use decriptexd exe from version 1.00 put on your GP4 folder. After using GP4 Master, you can swap back to patched exe. If yu don't like manual way, you can create batch file (.bat) to do the swap trick:
@echo off
ren gp4.exe gp4_v102.exe
ren gp4_v100.exe gp4.exe
c:\somewhere\gp4master.exe
ren gp4.exe gp4_v100.exe
ren gp4_v102.exe gp4.exe
exit
In reality, doesn't matter who's
right but most important is who's
left.