Linux Ubuntu 10.10 2.6.35-22-generic.
File Size 908kb.[102 pages]

Error Displayed by Terminal:
[Debug 16:21:45.497] Starting PdfMod
[Debug 16:21:45.564] Loaded custom AccelMap from /home/me/.config/pdfmod/gtk_accel_map
[Debug 16:21:45.590] Cache directory set to /home/me/.cache/pdfmod
Exception in Gtk# callback delegate
  Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
System.InvalidOperationException: Indirect reference without value.
  at PdfSharp.Pdf.PdfDictionary+DictionaryElements.GetValue (System.String key, VCF options) [0x00000] in <filename unknown>:0 
  at PdfSharp.Pdf.Advanced.PdfCatalog.get_Outlines () [0x00000] in <filename unknown>:0 
  at PdfSharp.Pdf.PdfDocument.get_Outlines () [0x00000] in <filename unknown>:0 
  at PdfMod.Gui.BookmarkView.SetDocument (PdfMod.Pdf.Document new_doc) [0x00000] in <filename unknown>:0 
  at PdfMod.Gui.Client+<LoadPath>c__AnonStorey10.<>m__22 () [0x00000] in <filename unknown>:0 
  at Hyena.ThreadAssist+<BlockingProxyToMain>c__AnonStoreyF.<>m__4 () [0x00000] in <filename unknown>:0 
  at PdfMod.Gui.Client+<RunIdle>c__AnonStorey14.<>m__21 () [0x00000] in <filename unknown>:0 
  at GLib.Idle+IdleProxy.Handler () [0x00000] in <filename unknown>:0 
   at GLib.ExceptionManager.RaiseUnhandledException(System.Exception e, Boolean is_terminal)
   at GLib.Idle+IdleProxy.Handler()
   at Gtk.Application.gtk_main()
   at Gtk.Application.Run()
   at PdfMod.Gui.Client..ctor(Boolean loadFiles)
   at PdfMod.PdfMod.Main(System.String[] args)
me@ubuntu:~$

Error can be reproduced, every time the File is loaded, but smaller files [50 pages] are being opened. :)

Dont know if it is a bug.