Check your AntiVirus, because the Launcher is packed by ASProtect like the Runnable[Gunz.exe]. Some Antiviruses can't detect the EXE file because of the encryped headers, etc so it stops it or destroys its' headers automatically^^ which makes the file useless because it can never run then.
Try Re-Installing CTGunZ and allowing Gunz.exe and the Launcher in your Antivirus list =)