Shell Cmd Works on Some Computers, But Not Others

[aerodoc]

On some computers/companies, the shell command will not run.

I am using this code, but have used other approaches to call a windows command shell:
http://www.cpearson.com/excel/ShellAndWait.aspx

It stops here, which may give an better idea about why it won't run the command shell:

ProcHandle = OpenProcess(SYNCHRONIZE, False, TaskID)
If  ProcHandle = 0 Then
    ShellAndWait =  ShellAndWaitResult.Failure
    Exit Function
End  If

My best guess is that this computer system/company has incorporated something that restricts Excel VBA from actually running the shell command. Perhaps this is set by IT or anti-virus, etc.? I suppose this might be a security measure/setting?