I'm having an issue with unwanted lines being added to files output by a cron job.

I have a script in /etc/cron.hourly which selects some data from a mysql database and saves it in a text file in /var/www. When I run the script as root, it does exactly what I expect it to do. When the script is executed by cron, it creates the same file, but prepends the following three lines at the top of the output file:

::::::::::::::
/var/www/outputfilename
::::::::::::::

I can't for the life of me work out how to stop this unwanted behavior. The line in /etc/crontab for cron.hourly is the default "44 * * * * root cd / && run-parts --report /etc/cron.hourly". If I use su to change to being root and do "cd / && run-parts --report /etc/cron.hourly" the script runs as expected and the output doesn't have the mysterious additional 3 lines. I've also tried removing the --report flag from the run-parts command in case that was somehow connected, but no joy. Finally, perusing the cron log output in /var/log/syslog just says cron.hourly ran without giving any additional information.

Any suggestions on solving this weird problem most welcome..