TheLastRipper on Xubuntu 11.10 gives System.MissingMethodException: Method not found: 'System.Type.op_Inequality'.

[EA de Zeeuw]

dezeeuw@XFCE:~$ thelastripper

Missing method System.Type::op_Inequality(Type,Type) in assembly /usr/lib/mono/2.0/mscorlib.dll, referenced in assembly /usr/lib/mono/gac/gtk-sharp/2.12.0.0__35e10195dab3c99f/gtk-sharp.dll

Unhandled Exception: System.MissingMethodException: Method not found: 'System.Type.op_Inequality'.

  at Gtk.Window..ctor (System.String title) [0x00000] in <filename unknown>:0 

  at MainWindow..ctor () [0x00000] in <filename unknown>:0 

  at MonoClient.MainClass.Main (System.String[] args) [0x00000] in <filename unknown>:0 

[ERROR] FATAL UNHANDLED EXCEPTION: System.MissingMethodException: Method not found: 'System.Type.op_Inequality'.

  at Gtk.Window..ctor (System.String title) [0x00000] in <filename unknown>:0 

  at MainWindow..ctor () [0x00000] in <filename unknown>:0 

  at MonoClient.MainClass.Main (System.String[] args) [0x00000] in <filename unknown>:0