Mac client file transfer weirding out

[DaShard]

Here's what happens:

1)... The 'Fileserver' is win2k with some biigggg Quark data files. (Also, SFM on ths win2k server)

2)... The 'Citrixserver' is 1.8 on top of Win2k. (no sfm)

Scenario:

Mac client logs on to 'Citrixserver' - no problem. Then, File transfers from 'Fileserver' to the Mac back home - initiated thru 'Citrixserver' (say 20 to 40 MB files)

Results:

Quark Mac files cannot be opened or recognized at Mac Person's home. Microsoft Docs and text files work just fine!!

Question:

why don't these quark files maintain integrity during the file transfer??? - yes we have DSL.

Extra info:

MS Office is installed on both 'Fileserver 'and 'Citrixserver'.

Thanks.