First step to do is go and check the cron jobs, you can do it by going to Settings > Company > Automation and look for a cron job with a spinner next to it.
After so long a clear cron job link will appear so you can skip the cron job. To find out the offending cron job you can use the following MySQL query: SELECT * FROM `log_cron` WHERE `run_id` !=0 AND `end_date` IS NULL ORDER BY `start_date` DESC;.
Thanks to Tyson for the tutorial.
Joseph H also adds that the imap PHP function is required for downloading tickets.
