PDF Filter error

[edm3]

I'm getting this error when trying to export a 2 page (tabloid) .pdf for printing. I am running tests with the different export options, as I am trying to get a good sense of the differences.
Has anyone got any idea of what this error is caused by?

Another question: Attached is an image showing a 'gloss' appearance I put on a colour swatch. The top, white colour has both a flat transparency and a bit o feather. At ~1300%, it looks like shite. Does anyone know any tricks of getting around this?

Thanks!