Qmail won't pre-process mail

[Blaksmith]

I have a strange error that I have encountered twice so far. What happens, is that qmail will run fine for 3 - 4 days, and then all of a sudden it will stop processing mail. With my qmailctl stat, this is the output I get:

/service/qmail-send: up (pid 6430) 312358 seconds
/service/qmail-send/log: up (pid 6431) 312358 seconds
/service/qmail-smtpd: up (pid 4127) 12208 seconds
/service/qmail-smtpd/log: up (pid 6433) 312358 seconds
messages in queue: 8
messages in queue but not yet preprocessed: 2
/service/qmail-pop3d: up (pid 4126) 12208 seconds
/service/qmail-pop3d/log: up (pid 6435) 312358 seconds

The only way that I have been able to fix it is to restart the box.

I am running Gentoo, kernel 2.4.20-gentoo-rc2.

Does anyone else know if there is a way to get it to force the preprocessing? I have tried every conceivable thing possible. I really don't want to reboot the box, because there are a ton of things that need to be re-started manually. (mainly non-root user programs)

Thanks in advance for your help.
Blaksmith