fatal: accept connection: Invalid argument

[Duane Hill]

I've been getting a bunch (more than 50) per day of the errors in the 
subject in the /var/log/messages.

The server is running FreeBSD 5.5-RELEASE-p9 amd. This is an email server 
that is doing spam filtering and is running Postfix 2.3.7.

I do have another server that is running FreeBSD 6.1-RELEASE-p10 i386 with 
Postfix 2.3.7. This one is only getting less than 10 of these errors per 
day.

I've done some searching and can't come up with a conclusion as to why 
this is happening. Can anyone shed some light?