Autosave some time not working

I have 2 pdfcreator printers, default one with autosave feature and the other one with standard settings.

I have a program that generate a pdf file from each doc document found into specific folders. All works fine but sometime (1-2 time on ~900 printed documents) appear the pdf property page with Cancel - Save - ... buttons. Why?

OS: Windows XP SP3
PDF Creator version: 1.1.0