invalid picture error

[Liam]

Some, not all, of my clients running Excel 2002 on XP are
getting an "invalid picture" error message. The only
picture I am using is a TIFF file on a user form, which
only shows for 2 seconds upon opening the file. They get
the error message upon opening the file, AND they get it
when their mouse rolls over any control (option button,
command button). The picture property of the TIFF image
says (Bitmap), so it seems that Knowledge Base article
175918 does not apply. Any ideas?

Liam