Joel Pearson wrote in post #1069478:
> Joel Pearson wrote in post #1069477:
>> Joel Pearson wrote in post #1069476:
>>> Bartosz Dziewoski wrote in post #1069474:
>>>> It works for me on Win XP. What is the return value of #system call?>>>>
>>>> Have you tried using backticks or Kernel#spawn instead?
>>>>
>>>> -- Matma Rex
>>>
>>> Thanks for your response.
>>> Spawn and backticks both work with CUI but not GUI. I'll try out another
>>> PC and see if it's my interpreter that's acting up. I'll reply with the
>>> results.
>>>
>>> Joe
>>
>> It works in Windows XP but fails on both Win7-64 machines I have acess>> to. Looks like WinPE platform issue?
>
> I have tried the attrib command on Windows 7 independantly of Ruby and
> it works from both the command console and the Run command. I can only
> assume that the command isn't being properly passed by Rubyw.exe on
> post-XP Windows systems.

Based on further rb/rbw testing on Win7, it looks like GUI doesn't allow system commands that would normally be linked the the console, like attrib or cmd. Notepad launches fine from both of the interpreters. Interestingly the system command returns true even when it has no effect.
I disabled User Account Control, and checked that the permissions are the same for CUI and GUI, no change. It must be something in the exe itself.