Digital BW, The Print

I'm having a problem installing QuadtoneRIP 2.0. The installer tells
me:
  "There were errors installing the software--Try Installing Again". 
This message has shown up after every  (many) attempts at installing 
QuadtoneRIP, although there previously was no problems with 
installation of 
Gimp-Print (4.2.6) and ESP  Ghostscript 7.05.6.

The Print-Gimp Error log shows a series of messages:
 "Filter (pdftops, textops, imagetops, imagetoraster) cannot be found"

Can someone offer a clue as to what went wrong (and the reason for
those 
missing filters)? BTW I have to admit being a neophyte with OS
10.2.6, having 
just upgraded from 9.2.2.

Phil