QTR-Quadtone RIP

I'm printing with QTR to both a 4000 and a 7600 from 10.3.9.
Everything has been great until a couple of days ago. Now no matter
what I do, I get a Command Error when attempting to print to the 7600
(the 4000 is fine). The Epson driver prints fine, it's only QTR. I've
tried different files, reinstalling QTR, unplugging and replugging in
the printer, changing my brand of breakfast cereal. What am I doing wrong?
Any help would be appreciated.
Thanks,
-Alan