JimF,
What type of file is it? A plain text file should work well on any platforms. Is it plain text, or another format like rtf?
Have you checked if your data contains any special characters, like characters with accents, mac-specific characters, etc? Such characters could maybe cause problems on a PC environment.
Have you tried printing in both Printer Centric and Optimized PostScript? In version 5, Optimized PostScript was called "Run Locally". So if you had "Run Locally" checked, try using Optimized PostScript in version 6.
Regards,
Rapha