SMDUpd hangs with 99% cpu

Linux RedHat 3.0ELTrendMicro ScanMail 3.0

Domino 6.5.4

The SMDupd process hangs with 99% CPU and eventually crashes the Domino server, either kicked of manually or scheduled. If scheduled then we end up with multiple SMDupd (27 before one server finally gave up).

No configuration changes have been made to the servers for months. And up to about two weeks ago they were behaving themselves.

Any one else seen this?