Hello,
I would like to inform you that there is no size limit for creating PDF's or PS files in QuarkXPress.
Please try to delete the Jaws folder and then see the results. Jaws folder is located in Mac HDD / Applications /QuarkXPress 6 folder.
Moreover,you can also compress the PDF files by perform the following steps:-
*Go to File > Export layout as PDF
*Click on the options button in the Export as PDF window
*Select the Job options tab
Choose the compression for color images and grayscale images as Manual jpeg high and then create the PDF.
I hope this information helps.