I don't know. I never had that problem with VPDF. In my case some PDFs where still not printable with VPDF: the printer tries to start (can here it's running-up noise), but then stops. Interessting: These files can be print in APDF and also in VPDF after converting it in a online-PDF-converter from "PDF to PDF". Seems that something changed during that procedure......

And think about: Sending a PDF directly to the printer is not the same as converting it to postscript and send it then (as VPDF does). Zukow is reading here too and I think he will find the problem.