Defunct sub-command while reading TOC

When attempting to rip a DVD, dvdrip hangs while reading the TOC.  The 
first command never returns.  A ps shows it as defunct.  Here's the log:

Sat Jul 19 15:47:16 2008 Start job 'Read TOC (lsdvd|tcprobe)'
Sat Jul 19 15:47:16 2008 Start job 'Read TOC (lsdvd)'
Sat Jul 19 15:47:16 2008 Executing command: execflow lsdvd -a -n -c -s 
-v -Op \/dev\/scd0 2>/dev/null && echo EXECFLOW_OK

And a 'ps':

$ ps
  PID TTY          TIME CMD
10917 pts/2    00:00:00 bash
11971 pts/2    00:00:00 dvdrip
12115 pts/2    00:00:00 sh <defunct>
16492 pts/2    00:00:00 ps
$

I can run 'execflow lsdvd -a -n -c -s -v -Op \/dev\/scd0 2>/dev/null && 
echo EXECFLOW_OK' by hand Ok:

$ execflow lsdvd -a -n -c -s -v -Op \/dev\/scd0 2>/dev/null && echo 
EXECFLOW_OK
our %lsdvd = (
  device => '/dev/scd0',
  title => '<snip>',
  vmg_id => '<snip>',
  provider_id => '',
  track => [

<snip>

  ],
  longest_track => 1,
);
EXECFLOW_OK
$ echo $?
0

Here are my system's vital stats:
Centos 5.2 x86_64
  Linux hostname 2.6.18-92.el5 #1 SMP Tue Jun 10 18:51:06 EDT 2008 
x86_64 x86_64 x86_64 GNU/Linux
DVD::Rip 0.98.7 from the DAG repository
perl 5.8.8
perl-Event-ExecFlow 0.63
DVD - /dev/scd0 - SATA II - Optiarc DVD RW AD-7200S

Any help would be appreciated.

    --Dave