PSGML: DTD found only in DOS mode?

[Jen]

ive just started to use PSGML mode to edit XML documents, and im
having a funny problem that i couldnt even track down at first.

The files im working with begin like:

<?xml version='1.0' encoding='ascii'?>
<!DOCTYPE MYPROJECT SYSTEM "MyProject.dtd">

i have an XML catalog file set up, with a relevant line reading:

<system systemId="MYPROJECT"
uri="file:///usr/local/share/xml/MYPROJECT/MyProject.dtd" />

By accident the file i was working with when i was trying to learn
PSGML was something from a windows computer and it shows a little
"DOS" on the left side of the status line. Everything worked fine.

Then i tried to work on another file, and got a message 

External entity MYPROJECT not found
  System identifier MyProject.dtd

The only variable is the DOS-ness of the file; when i take the
original, working file and run it thru dos2unx, then PSGML gives the
error message.

What should i do? Surely PSGML can work with Unix files!!!! Is it my
catalog thats the problem, or what? i cant change the DOCTYPE line,
its something in all our files and i cant edit it.

Thanx!

Jen