Formatting Issue – Office XP/Office 2000

I’ve noticed an issue with users who share files between Office XP and Office 2000. It seems that when a user with Office XP creates a Word or Excel file and then that file is opened by the Office 2000 user, or vice versa, the formatting gets messed up.

The user of the XP version has tried to save as an Office 2000 format, but to no avail. Any ideas on what might fix this?

Thanks!