Could be a variation of the issue described at
http://support.microsoft.com/?kbid=827302 "TIFF image appears
dark when you insert it into PowerPoint 2003".

Jen wrote:

I have a watermark inserted using the Format -- Background -- Printed
Watermark function. On the screen it looks great. But when I print, the
watermark isn't semitransparent (as I have set) - it is black and it obscures
the text.

Anyone experienced this before or know how to fix it?

TIA,
Jen