Crontab -e Saving Issues

Hi Everyone,

I have a series of drupal 6 sites running and have already configured the crontab. All the cron jobs are currently running with no known issues.

I have recently released a new drupal 6 site, tried to update the crontab -e and it refuses to save.

I have also looked at the permissions and have ensured that the permissions are as follows.

-rwsr-xr-x 1 root root 315384 May 19 18:15 /usr/bin/crontab

The cron jobs run off of a dev server (Ubuntu) which then feed into the live websites (Red Hat) (not ideal, but its what ive been given to work with)

Any help would be greatly appreciated.
Sammyb