Event ID 478 containing error -613 is due to either a software conflict or a hardware issue on the Exchange 2000 server. This error frequently occurs when third party Exchange 2000 utilities are installed, which are designed to augment or change the functionality of Exchange. These errors generally only occur during backup, as this is when the mailbox stores are most taxed.
In order to rule out the possibility of a software issue, all third party Exchange utilities must be uninstalled. Following uninstall, a reboot must be performed. Stopping services for Exchange utilities is not sufficient, as many employ filter drivers designed to operate independently of the program's service.
Most frequently, this issue is encountered when GFI Mail Essentials is present on the Exchange 2000 server. Of course, other programs of this type have the capacity to cause the same problem.