On trying to multiply a vnl_matrix_fixed matrix with another vnl_matrix_fixed matrix MITK crashes. The "Bad Exec Signal" is sent from method vnl_matrix_fixed_mat_mat_mult() in vnl_matrix_fixed.h (line 776). This multiply method is called by itkGlobalTractographyFilter.cpp in line 73.
No sure if this happens only in the itkGlobalTract filter or applicationwide in OSX.