Maybe it's not related to the script but to the dbms itself.

I have no Mysql experience but the concepts should be the same...

Check the transaction log file used for undo/rollback blocks;maybe it has no room to accomodate for all those inserts.If that is the case then just increase it's size or disable logging.

Check the dbms error log for clues

Check the temporary working directory which is used by Mysql,do a simple df -k,maybe it is filled up.