Strange problems with subprocess

[Michele Petrazzo]

Hi all. I have a simple "ping tester" program that, every 1 minute
(execute by linux crontab), create, with subprocess, a
"ping -c 1 my_addrs". All work, but sometime (about 1/2 times at a day),
I receive this error message:

File "/exports/srv-wipex/net_test/ping_tester.py", line 88, in pyPing
   cmd_p = Popen(cmd, stdout=PIPE, stderr=PIPE)
File "subprocess.py", line 543, in __init__
   errread, errwrite)
File "subprocess.py", line 970, in _execute_child
   data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB

What can be that raise this?

Python 2.4 in deb etch

Thanks,
Michele