macphisto's right. (on two accounts.) but assuming you're not going to run out and drop $1000 on InDesign, start with the possibility that it's a font thing -- Quark can get all screwy when fonts go bad.
restart your machine. if you're using ATM Deluxe: close all open fonts (except the ones in your system folder, but ATM won't let you close those anyway) and under ATM's preferences, turn off auto-enable. restart again.
open quark and try to recreate the problem -- if it doesn't happen, it's a font thing. now you get to try to figure out which font it is... fun, fun, fun. with auto-activation still off, activate half of your fonts via ATM. see if quark crashes. if no, turn off all fonts and activate the other half. see if quark crashes. when you figure out what half of the fonts has the bad font, turn off half of that half, and figure out which quarter of your fonts has the bad one. continue in that manner until you narrow it down to one. trash it and hope that solves the problem...