Thanks guys for your help.

As to installing the service - I use a script I found on the net. It works so I dont worry about that.

I have tried:

ShellExecute(print => $file, 0, 0, 'SW_HIDDEN');
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This works manually and not as service. AcroRd32.exe is called by that class and it does never quit.

I also installed ghostscript and tried:

system "c:\\apps\\gswin32c.lnk -dPrinted -dBATCH -q -sDEVICE=mswinpr2 
+-dNoCancel -dNOPAUSE \"$file\"";
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Works manually but not as service.

Interestingly, a dialogue box comes up to OK or Cancel the print (which probably is the show stopper for the service to work).

I assume if I can get the dialogue box to not appear I have a solution.

According to some ghostscript forum the -dNoCancel options is supposed to remedy that but in my case it does not.

I'll keep digging...