Quark 7.5 Will Not Print In Snow Leopard

I've been running my networked G5 (OS 10.4.11) for years with no problems using Quark, PhotoShop, Illustrator, etc. I recently bought a new iMac (OS 10.6.2) and migrated the G5 files to iMac. Worked through a few bugs and adjustments, however QuarkXpress documents will not print to my printers (Xerox Phaser 5400 and Lexmark C540). I can print simple Quark documents (text only), but as soon as I try any complex documents, the job spools to the Phaser and then is cancelled. On the Lexmark an error of "900 Firmware Error" appears. All other applications, ie, InDesign, Photoshop, Illustrator, Acrobat and various other applications print fine to both printers. Obviously it's an issue with the Quark software, but I haven't been able to resolve. Any insights?