I found this useful post by “MalloryKevin” at Apple’s Support Forums:
To all those with Quark 7.5 crashes on Snow Leopard, I think I’ve found a solution.
As the IT guy, I always experiment with new OSes and our current versions of software before I subject the rest of the company to it. So, I had Quark 7.5 running fine on my iMac with Snow Leopard 10.6.4, so I knew it would work.
But then I went to install a new Mac Mini computer for another user in our company. I used Migration Assistant to move everything across. Quark 7.5 crashed upon starting. Years ago we had been advised by Quark to make a Preference folder in the Quark folder, so I tried trashing those prefs, same problem. Then I opened Library/Preferences (not user library, the one at the Hard Drive level) and found another Quark Folder there. Trashed that, it now opens…
He seems to have run across one of the reasons you don’t want to create a Preferences folder in the QuarkXPress application folder. For more information on that, see my previous post. You can read the complete discussion page here.
Jay Nelson is the editorial director of PlanetQuark.com, and the editor and publisher of Design Tools Monthly. He’s also the author of the QuarkXPress 8 and QuarkXPress 7 training titles at Lynda.com, as well as the training videos Quark includes in the box with QuarkXPress 7 . In addition, Jay writes regularly for Macworld and Photoshop User magazines and speaks at industry events.