ok, the program is completly corrupted, this is the cause of the initial problem and it will need to be reinstalled.
Your in a tightspot as you cant on this computer use the latest version as it wont run on this Mac, its too old,
Its really hard to come by and I only found 1 copy here.http://www.amazon.com/Quark-Inc-119700-QuarkXpress-6-0/dp/B0000A1GQ0
Price is really expensive though.
I think its amazing you got so many years out of it, really, but your only left with
- Locating your disk so you can install it again
-Buying the disk I gave the link for
-(and this I would advise) upgrading the Mac to a current standard so you can purchase the latest version.
But for your situation, your stuck with one of these three options.
If you would like any additional information or assistance, please do not hesitate to let me know.
Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.