Sophie problems

Hello,

I'm running Postfix 2.0.18, Amavisd-new (p8), SA, Sophos 3.79, latest
Sophie.

On our primary mail server Sophie will randomly just stop working.
Luckily Postfix queues up all the mail when it happens. ps -aux shows
Sophie still running, but I have to "killall -9 sophie" and then start
it again in order to get things working.

Where should I look to figure this one out? I'm running with the default
config files.

Thanks,

- Darren