PDC Creator Server as service occasionally not write PDF

I have installed PDF Creator Server 1.7.3 on a MsWindows2003 Server italian.
PDF Creator run as Windows Service

The service named [PDFCreator] is up and start automatically.

I configured PDF Creator to autosave in C:\OutputPDFCreatorDocumentale\

A batch print 
some documents to PDFCreator then I find the PDF files in my directory.

Sometimes the batch try to print, I view in EventViewer/system the event:
Information EventID: 10 User: xxx\administrator Computer: yyy l
documento 91, 1421150004998 appartenente a administrator è stato
stampato su PDFCreator attraverso la porta pdfcmon. Dimensioni: 117448
byte; numero pagine stampate: 1.

Then event:
Type: Information EventID: 13 User: NTAUTHORITY\SYSTEM Computer: yyy Il documento 91, 1421150004998 appartenente a administrator è stato eliminato su PDFCreator.

but I dont’t view my PDF in my directory.

When I log as administrator in my server xxx ALL PDF are created in my directory with DateTime of my login.

additional information:
PDFCreator service RUN as SystemAccount (but
same problem if it run as Administrator).

Thank for your help