A stupid thought probably but...
It seems you are asking this for professional matters (for work or so?) so can't you try to open the file in InDesign (version 2 if possible).
I don't really have an answer on the problems, but i know Quark isn't really THAT platform compatible, pc files do give problems on Mac... not to mention the other way around
About the ZIP drive, i think the person made a "collect to publisher" using that function on Quark, or the "PreFlight" software (damn, i have a feeling this is called different.. that software).
Hope you solve it at any way