PDF stuck on flattening then fails to print

I am having the same problem described in this thread: http://forums.adobe.com/thread/989360

My clients get this a couple times a week with PDFs I create, but they always print just fine for me. Today I finally got one that won't even print for me. As a note I am using Reader XI and most of my clients are using Acrobat (versions ?)

The hackish fix up to this point has been to "Print to Image" but I want a better solution if possible. I also use NitroPDF and it prints the PDFs without problem.

My PDFs are dynamically created using the EO.PDF .Net library (http://www.essentialobjects.com/). I am working with the library developer to figure this out, but without some idea of what Reader and Acrobat are objecting to, he can't do much more.

Here is a link to the offending PDF: http://www.maphazardspro.com/assets/50-13-05348-001.pdf.  On this particular file, the problem is with printing page 4.

I have found other references to transparency flattening causing some issues with large documents. The offending page does have many PNGs with transparency.

Thanks!

Brad