slide blinks rapidly when I put a shadow and can not see presentation.
Turn down your hardware acceleration.
See How to set graphics hardware acceleration back
http://www.rdpslides.com/pptfaq/FAQ00129.htm

Signature
Echo [MS PPT MVP]
http://www.echosvoice.com
Fixing PowerPoint Annoyances
http://www.oreilly.com/catalog/powerpointannoy/
> slide blinks rapidly when I put a shadow and can not see presentation.