When viewing a PDF, some areas are blacked out, such as cells on a table. However, when I print them, they look fine. I have made sure "Show large images" is checked, as suggested from other forums.
I am not sure, but it may be that you are looking at it to different versions of the products. What versions of Acrobat and Reader are being used. Sometimes, transparencies have some display issues, but I really do not know how to handle them.
Acrobat 9 and Reader X are not compatible! It is an unsupported combination. Only Acrobat X and Reader X are compatible. So the issue could stem from that. The issue could also stem from a video driver problem. See if you can turn off any video driver acceleration.
I actually downloaded Reader X to see how a PDF appeared different from Acrobat 9. Their compatibility should have nothing to do with the viewability of the opaqueness in a PDF. Again, I only downloaded to compare/contrast.
I will, however, take a look at the video driver accelaration.
I don't think this is solved yet, though.