Pete,
I sent the email from the help menu of pingplotter and received the confirmation.

One other thing that I would like to mention is that the computer running Pingplotter Pro is actually a guest virtual server on a VMWare ESXi server. The server is pretty beafy with dual quad core 2.5ghz xeon processors, 16gb of ram and 10k SCSI hard drives. So I cant see the issue being due to lack of resources.