Quark? We gave up on Quark years ago. InDesign produces much better type and not having to deal with constant crashing in OS 7, 7.5, 8 and 9 makes working with OSX 10.3 + InDesign much more productive. With OS 7.5, it was hard to go a day without having to reboot at least once if not several times.
With OSX I don't think twice about having InDesign, PhotoShop, Mail, Safari and five or six other applications running at the same time. With OS 7.5, bringing an application to the front meant bringing all that application's windows to the front. OSX's method of just bringing the window you selected to the front while letting you see the other application's windows is so much better. My suggestion is to dump Quark. That's the source of your frustrations.
Mac OS 7.5: Better than Tiger Will Ever Be