I just glanced through the source code on Netlabs (which unfortunately is older than the last release, the code for which appears to be lost).
The return code 1 is coming from Ghostscript, it doesn't appear to be a system error. So I assume Ghostscript is at least loading successfully.
There should be a logfile in %TMP%\pdfwrite.msg. You could try examining it for clues. It should contain, among other things, the complete command line used to invoke GS, which you might try running manually to see if you get any more information.
FWIW (from looking at the source code), the command line should be:
gsos2 -q -Ic:\programs\gs\gs8.71\lib;c:\programs\gs\gs8.71\..\fonts;c:\psfonts -dBATCH -dNOPAUSE -dNOPLATFONTS -sFONTPATH=#c:\psfonts -sDEVICE#pdfwrite -dPDFSETTINGS=/screen -dEmbedAllFonts=true -sOutputFile#"pdf_file" "ps_file"
(assuming C: is your boot drive)