Acrobat Pro - Visio to PDF Conv - Blurring Underneath Semi-Transparent Rectangles Used on a Layer for Highlighting

Hi Everyone,

I'm using Acrobat Pro XI to convert a large Visio document into a PDF.  In the Visio document I am using semi-transparent rectangle objects, which are all assigned to their own layer, to create a really cool switchable "highlighting layer." The highlighting layer then appears with a checkbox in the resulting PDF layer. If the PDF layer is switched off in the resulting PDF, everything looks great. When the highlighting layer is switched on in the PDF, the highlighting appears, but all the graphic objects, text and lines that are seen though it get blocky and blurry. It's kind of like an anti-alias gone very bad. The bigger the Visio document is (in size) the worse the effect becomes. If I place the highlighting layer behind the all the other objects in the Visio drawing, then there is no bluing/blocking in the PDF, but that won't work for what I need to do. Any help is very much appreciated!  Everything looks perfect in Visio itself. Any help is GREATLY appreciated!