I just ran into this nasty bug at a customer I switched recently to X. Everything worked fine except Photoshop 7 when we tried to print out a simple JPEG file. The result? It ended with us removing the power cable from the printer because it had already printed out 50 pages and one line of garbage text on every page.
I set the HP LaserJet 2100 TN printer via the HP Utility from an OS 9 machine from 1200 to 600 dpi default resolution and voila, everything in PS 7 prints just fine as it should.
[robg adds: I can't confirm this one, but thought that it might help someone...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030218152727652