missing postscript when printing with adobe acrobat

Hello,

When printing with a printer driver in Adobe Acrobat (all versions) a part
of the postscript data is missing in the postscript printfile. With a part,
I mean a part of the beginning of the postscript file. If I print to file
and I want to convert the file to PDF with Acrobat Distiller, the
application says that the postscript is corrupt. It only happens when we
turn on the option in the driver which pops up a dialog during the print
process (On the printer driver event: StartdocPRE). Why does this happen?

cheers
A printer driver developer.