Printer keeps stopping

[Richard Hall]

I have several printers set up using cups.    Every now and again a 
couple of the print queues keep stopping.    I clear the jobs and 
restart them with no problem,  then a couple of days later someone will 
complain that printing has stopped working,   I look at the web admin 
interface and they are stopped again.    Can anyone think of a reason 
that would cause this behavior?

Cups version 1.1.21 running on Gentoo.
Printer is an Oki B8300

Thanks