I’m having the same problem .
I have a product list containing about 400 items, and the dataflow of magento does stop after a while.
I had once a PHP error that explain that my script was using more mamorie than alocated.
My server got 34 MB RAM allocated to PHP script.
I’m trying to cron it but i’m not able to generate a script that uses the dataflow importation via a Bash without any documentation on the classes structure of Magento.
Do any one person know how i could cron the importation ?