subprocess.check_call() fails ... but only on my production machine

[Chris Curvey]

I've got a python program running on windows that executes a command-
line script.  The command being executed is:

>>> print cmd
"C:\Program Files\ImageMagick-6.6.1-Q16\convert.exe" -density 72x72 "c:
\temp\choicepoint 2010-01 Stmt_p1.pdf" -quiet -region (612.0x70.0+0+0 -
blur 0x3) -region (612.0x709.0+0+83.0 -blur 0x3)  "\\fs4\w
\13\132651\BILLING_PROOFS\132651_choicepoint 2010-01 Stmt_p1_r1.pdf"

>>> subprocess.check_call(cmd, shell=True)

if I  run the command thru python subprocess.check_call() on my
Windows 7 (development) machine, it works fine.
if I run the command in a command in a command window on my windows
2007 server (production) machine, it works fine.
if I run the command thru  python subprocess.check_call() on my
Windows 2007 server (production) machine, it fails.

I'm running both the Python script and the command window as the same
user.  Can anyone give me a hint as to what might be happening...or a
way to get more information about what the error is?  (All I get is
"Command returned non-zero exit status 1")