Some esoteric information that could help with TIFF and JPEG problems

[Jim Gordon MVP]

If a picture uses the Tagged Image File Format (TIFF) format, PowerPoint
for Mac does not support the following graphic features:
* Multiple alpha channels
* Formatting for IBM PC
* The Lab Color format

Additionally, Joint Photographic Experts Group (JPEG) pictures that use
the cyan-magenta-yellow-black (CMYK) color model are not supported.

Futher details:
http://support.microsoft.com/?kbid=895083

-Jim