I have one of the strangest bug I come accross your software. Before I tell you the issue, I just want to let you know that HelpDesk is a great support ticket system, very intuitive and practical at the same time.
The bug I came accross was, in the Ticket section of the Settings. I changed, the "Guests can use email to ticket?" to Yes, for I originally had it to "NO", the bug appeared in that it kep creating blank tickets. I noticed that those that were created had the subject as Email Piping and body text: "ticket/Answer from support@ has not been created."
It created a ticket every 2 minutes, this is very strange, since it doesn't have a cron function. So, I don't know how that came about. It was very frustrating, so I had to resort to install a backup (only the db backup), and that seemed to fix the issue. For your information I'm using helpdesk 1.5 and use original pipe.php file (unmodified).
Please let me know if you can replicate this and/or what to look for in your pipe.php file to tackle.