Windows fatal exception: access violation

Current thread 0x00002ce4 (most recent call first):
  File "DisplayCAL\CGATS.pyc", line 429 in get
  File "DisplayCAL\CGATS.pyc", line 417 in __getitem__
  File "DisplayCAL\CGATS.pyc", line 583 in __str__
  File "DisplayCAL\CGATS.pyc", line 561 in __str__
  File "DisplayCAL\CGATS.pyc", line 2120 in write
  File "DisplayCAL\worker.pyc", line 10902 in measure
  File "DisplayCAL\worker.pyc", line 1556 in __call__
  File "wx\lib\delayedresult.pyc", line 267 in wrapper
  File "threading.pyc", line 754 in run
  File "threading.pyc", line 801 in __bootstrap_inner
  File "threading.pyc", line 774 in __bootstrap

Thread 0x00003d9c (most recent call first):
  File "socket.pyc", line 206 in accept
  File "DisplayCAL\wxwindows.pyc", line 932 in connection_handler
  File "threading.pyc", line 754 in run
  File "threading.pyc", line 801 in __bootstrap_inner
  File "threading.pyc", line 774 in __bootstrap

Thread 0x000012b0 (most recent call first):
  File "wx\core.pyc", line 2166 in MainLoop
  File "DisplayCAL\DisplayCAL.pyc", line 16680 in main
  File "DisplayCAL\main.pyc", line 438 in _main
  File "DisplayCAL\main.pyc", line 451 in main
  File "DisplayCAL", line 6 in <module>