I'm using Gutsy, x86 and nVidia graphic card
Sometimes the crash is right after opening a file, sometimes scrolling it, sometimes modifying the zoom.
Sometimes a crash dialog is opened with a invalid backtrace, sometimes with a valid one, sometimes it's not opened at all.
Here's the backtrace generated after scrolling a bit the file for which I posted the link before.

(no debugging symbols found)
Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1236043376 (LWP 8835)]
[New Thread -1296061552 (LWP 8845)]
[KCrash handler]
#6  0xb6d38583 in strlen () from /lib/tls/i686/cmov/libc.so.6
#7  0xb2f76665 in ?? () from /usr/lib/libgs.so.8
#8  0x00000000 in ?? ()

Thread 1 (Thread -1236043376 (LWP 8835)):
#0  0xffffe411 in __kernel_vsyscall ()
#1  0xb6d915e7 in poll () from /lib/tls/i686/cmov/libc.so.6
#2  0xb6905839 in ?? () from /usr/lib/libX11.so.6
#3  0x08068b90 in ?? ()
#4  0x00000001 in ?? ()
#5  0xffffffff in ?? ()
#6  0xb690e67f in _X11TransWrite () from /usr/lib/libX11.so.6
#7  0xb6905c2f in _XRead () from /usr/lib/libX11.so.6
#8  0xb6906604 in _XReply () from /usr/lib/libX11.so.6
#9  0xb6901d04 in XTranslateCoordinates () from /usr/lib/libX11.so.6
#10 0xb70c3561 in QWidget::mapToGlobal (this=0x8158df8, pos=@0xbfad9c44)
    at kernel/qwidget_x11.cpp:1030
#11 0xb4f75db1 in ?? () from /usr/lib/kde4/lib/kde4/okularpart.so
#12 0xbfad9860 in ?? ()
#13 0x08158df8 in ?? ()
#14 0xbfad9c44 in ?? ()
#15 0xbfad9858 in ?? ()
#16 0xbfad98a0 in ?? ()
#17 0x00000748 in ?? ()
#18 0xbfad9988 in ?? ()
#19 0xb7089ea7 in QWidget::event (this=0x8158df8, event=0xbfad9c34)
    at kernel/qwidget.cpp:6138
#20 0xb7089ea7 in QWidget::event (this=0x8158df8, event=0xbfad9c34)
    at kernel/qwidget.cpp:6138
#21 0xb73d46f2 in QFrame::event (this=0x8158df8, e=0xbfad9c34)
    at widgets/qframe.cpp:657
#22 0xb746695f in QAbstractScrollArea::viewportEvent (this=0x8158df8, 
    e=0xbfad9c34) at widgets/qabstractscrollarea.cpp:926
#23 0xb74694ee in QAbstractScrollAreaPrivate::viewportEvent (this=0x8336bd8, 
    event=0xbfad9c34) at widgets/qabstractscrollarea_p.h:95
#24 0xb7469520 in QAbstractScrollAreaFilter::eventFilter (this=0x8329230, 
    o=0x83291a8, e=0xbfad9c34) at widgets/qabstractscrollarea_p.h:106
#25 0xb70383c8 in QApplicationPrivate::notify_helper (this=0x80653c0, 
    receiver=0x83291a8, e=0xbfad9c34) at kernel/qapplication.cpp:3550
#26 0xb7039566 in QApplication::notify (this=0xbfada7c8, receiver=0x8332720, 
    e=0xbfad9ea8) at kernel/qapplication.cpp:3319
#27 0xb7a8d550 in KApplication::notify (this=0xbfada7c8, receiver=0x8332720, 
    event=0xbfad9ea8)
    at /build/buildd/kde4libs-4.0.1/kdeui/kernel/kapplication.cpp:314
#28 0xb7ebf456 in QCoreApplication::notifyInternal (this=0xbfada7c8, 
    receiver=0x8332720, event=0xbfad9ea8) at kernel/qcoreapplication.cpp:532
#29 0xb704381d in QCoreApplication::sendSpontaneousEvent (receiver=0x8332720, 
    event=0xbfad9ea8)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:205
#30 0xb7098144 in QETWidget::translateWheelEvent (this=0x8332720, 
    global_x=676, global_y=440, delta=-120, buttons=@0xbfada08c, 
    modifiers=@0xbfada088, orient=Qt::Vertical)
    at kernel/qapplication_x11.cpp:3898
#31 0xb70a4502 in QETWidget::translateMouseEvent (this=0x8332720, 
    event=0xbfada53c) at kernel/qapplication_x11.cpp:3655
#32 0xb70a2960 in QApplication::x11ProcessEvent (this=0xbfada7c8, 
    event=0xbfada53c) at kernel/qapplication_x11.cpp:2922
#33 0xb70d1a7f in x11EventSourceDispatch (s=0x8068440, callback=0, 
    user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:137
#34 0xb6beb11c in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#35 0xb6bee55f in ?? () from /usr/lib/libglib-2.0.so.0
#36 0x08067698 in ?? ()
#37 0x00000000 in ?? ()
#0  0xffffe411 in __kernel_vsyscall ()

And this is the output on the command line, but it doesn't give any useful information I guess:
GPL Ghostscript SVN PRE-RELEASE 8.61 (2007-08-02)
Copyright (C) 2007 Artifex Software, Inc.  All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
Loading NimbusMonL-Regu font from /var/lib/defoma/gs.d/dirs/fonts/n022003l.pfb... 2939764 1380318 3499788 1925077 3 done.
GPL Ghostscript SVN PRE-RELEASE 8.61 (2007-08-02)
Copyright (C) 2007 Artifex Software, Inc.  All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
GPL Ghostscript SVN PRE-RELEASE 8.61 (2007-08-02)
Copyright (C) 2007 Artifex Software, Inc.  All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
Loading NimbusMonL-Regu font from /var/lib/defoma/gs.d/dirs/fonts/n022003l.pfb... 2939764 1380324 3499788 1925097 3 done.
GPL Ghostscript SVN PRE-RELEASE 8.61 (2007-08-02)
Copyright (C) 2007 Artifex Software, Inc.  All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
KCrash: crashing... crashRecursionCounter = 2
KCrash: Application Name = okular path = <unknown> pid = 8835
sock_file=/home/fe/.kde4/socket-fe-laptop/kdeinit4__0