Hope you can figure it out. Also glad to hear you're an Ultra-edit guy. I've been using this ancient version :-)
Before you beat your head on it too much, it might be useful to try it (if you can) on Windows XP.  If it works there but not on Windows 7, then you have a clearer idea of what you are up against.  I still am struggling to have a REBOL program call a Powershell script on Windows 7.  It works fine on XP.
another detail, it works if launched from within a command prompt...
This seems more and more related to the defective piping in windows graphical environments.
btw, sometimes specifying an /input   with a value of "^/^/^^/" solves a few command line apps which start asking for returns when they generate an error... I had this problem with a version of ssh I was using a while ago.
I used CALL with /output on XP soon. It works fine.
And my customers OS is Win7, and it works there too, after try a bit more.
I can check it at Wednesday at work, as it is holiday here tomorrow.
if I remember correctly, there was some issues about paths and quotes.
Try using FileMonitor from Sysinternals and see the paths and command-line arguments for the called application.
the command which fails is  "dir"   ;-)
Even with VISTA, I have problems using CALL and relative paths.
Changing paths and Woops! you are randomly teleported
did you put /SHELL ?
my application calls BCP.exe to import data to a SQL server database.
in /output string I try to FIND "error" word, and if exists, I popup an alert.
your /output is to a pre-initialized string right?
and try /show as well.
funny, I was trying something else and just saw that /show was still a refinement  and that works.
darn.  I havn't used /show for years.
but I actually found a better solution.
using cheyenne's Call  and  add  "Cmd /C" to the head of the command (without using  /show)
you must simply remove the  ^M  chars , but at least there are no command prompts popping up.
^M  chars from the piped output
That's a good solution.
rebol turns app dev times upside down.   2 hours to build an app   2 days to figure out how to launch a command line without crashing the app  ;-)

Last message posted 77 weeks ago.