[exim] Interupted system call

I'm wondering why I'm seeing these:


Connecting to cable1.net [204.251.15.172]:25 ... LOG: PROCESS
84524 delivering 1Gcnjb-000P81-IZ to cable1.net [204.251.15.172]
(timdoyle@???)
LOG: PROCESS
84522 delivering 1Gcnjb-000P81-IZ: waiting for a remote delivery
subprocess to finish
failed: Interrupted system call


I can't find much info about what Interrupted system call means.

thanks.

exim 4.53
freebsd 5.5
clamav .88.5
spamassassin 3.1.6