SOLUTION: Ok, so just stumbled across this thread with the crash on PDF import problem. I had the same trouble on an old but recently rebuilt MacBook Pro running Snow Leopard 10.6.8 and Vectorworks 12.5.3. After looking at all the above suggestions, including turning Quartz on and off (no difference) I found the solution was to get rid of some bad fonts! So I disabled the bad and duplicate fonts via Font Book and then also had to hand remove some really stubborn fonts from User>Library>Fonts and voila everything works again!!