WCT Error

Problem signature:
  Problem Event Name:	CLR20r3
  Problem Signature 01:	WarcraftTools.exe
  Problem Signature 02:	1.0.5.0
  Problem Signature 03:	561a1d73
  Problem Signature 04:	PresentationFramework
  Problem Signature 05:	4.0.30319.34209
  Problem Signature 06:	5348b261
  Problem Signature 07:	48d4
  Problem Signature 08:	26
  Problem Signature 09:	System.ArgumentNullException
  OS Version:	6.1.7601.2.1.0.256.1
  Locale ID:	1033
  Additional Information 1:	6417
  Additional Information 2:	64177a8af4304bfd545d1da8f2123c94
  Additional Information 3:	5aeb
  Additional Information 4:	5aebbf9bfd29e530d7a0f862cd272f69