Black parts in WMM-project

After working for hours with my WMM-project, importing both music, pictures
and small video files, using different effects and transitions, and text
boxes, I was very disapointed when trying to play it back..All my pictures
were black, but the videos and music were OK. I have understood that this
maybe is caused by too many different "things at the same time", and that WMM
doesn't handle this. My frustration is just: Why didn't it say so BEFORE (or
WHEN) I used too much features? All my work had to be done over again....
I have never seen any information about this when I have read about this
"fantastic program"...
--
anneki