enable threshold - (CRON) error grandchild #PID failed

[yossarianuk]

Hi.

As soon as I enable any thresholds in cacti (Thold 0.43) I get these errors in syslog (on polling - every 5 mins)

Feb 24 16:10:01 security1 /USR/SBIN/CRON[3638]: (cactiuser) CMD (/usr/bin/php /var/www/cacti/poller.php > /dev/null 2>&1)
Feb 24 16:10:08 security1 /USR/SBIN/CRON[3636]: (CRON) error (grandchild #3638 failed with exit status 255)
Feb 24 16:10:08 security1 /USR/SBIN/CRON[3636]: (cactiuser) END (/usr/bin/php /var/www/cacti/poller.php > /dev/null 2>&1)

Also email notifications are not sending - test email was fine.

Anyone got any ideas how to stop errors/get mail sent?

Regards