Network Printer Problem

Hi all,

I have a printer connected to a domain of about 10 PC?s.
It?s a big Xerox station connected directly to the switch.
The problem is that sometimes it prints nonsense ASCII characters
instead of the requested documents. The same thing happens sometimes
to a small inkjet HP connected to a workstation, so drivers can be ruled out.
I think it could be a network flow problem.
It doesn?t happen exclusively to multipage documents but also when trying to print one page!
The server is Windows 2000 Server and 8 workstations have WIN XP Pro and 2 have WIN 98.

Have you ever seen sth like this?
How can it be solved?

Thanx for your time,

Sakis