Have you done something fancy ? like displaying a filtered SubForm on the request form of your report ?
What I’ve noticed is that some printer driver handle pretty badly the shape control (rectangle, horizontal/vertical lines) on the reports … Have you got those on your report
The first thing I would do, is delete the ZUP file on the PC where this problem occur, and wait until it’s again reported before investigating further … a corrupted ZUP file might also be a reason …