python script hangs when run from subprocess

[Larry.Martell at gmail.com]

I have a python script and when I run it directly from the command line it runs to completion. But I need to run it from another script. I do that like this:

p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
rv = p.wait()
out_buf = p.stdout.read()

When I do this, wait never returns. If I trace the underlying script it's always in the same write to stderr that never seems to complete:

write(2, "/KA22/05Feb12/Images/12063LBO003"..., 24457

I run many other scripts and commands in the same manner, and they all complete, it's just this one. Anyone have any ideas why this is happening, and how I can further debug or fix this?

TIA!
-larry