pdftops from poppler-0.5.3 does not always produce correct postscript, so kpdf
does not work in some cases. An example generated with poppler-0.5.1-r1 and
poppler 0.5.3:

--- chp2-0.5.1.ps       2006-07-10 12:11:04.000000000 +0200
+++ chp2-0.5.3.ps       2006-07-10 12:00:51.000000000 +0200
@@ -5739,6 +5739,18 @@
 } bind def
 /CharProcs 1 dict def
 CharProcs begin
+[] 0 d
+1 i
+0 j
+0 J
+10 M
+1 w
+/DeviceGray {} cs
+[0] sc
+/DeviceGray {} CS
+[0] SC
+false op
+false OP
 /AH {
 43 0 2 -14 41 31 setcachedevice
 q

etc...

gs (esp or gpl ) crashes in this case