Konica Monolta bizhub 420 problems

I have a Konica monolta bizhub 420 on a network that for some reason
or another will not print sometimes and sometimes it will. when it
refuses to print it says that it was sent off and is printing but never
comes out the other end. we are running XP with 2003. its frustrating for
our users and as well as me. has anyone every heard of this?