Hi Alfonso, 

To test for multiple file selection I returned to the structural tab and selected a single structural file. I then ran the preprocessing starting at structural normalization and segmentation. I received the same error message (below). I've attached a screen shot of my structural tab. 
Michael



ERROR DESCRIPTION:

Error using cfg_util (line 835)
Job execution failed. The full log of this run can be found in MATLAB command window, starting with the lines (look for the line showing the exact #job as displayed in this error message)
------------------
Running job #1
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Error in spm_jobman (line 217)
Error in conn_setup_preproc (line 804)
Error in conn (line 503)
Error in conn_menumanager (line 102)
CONN v.14.n
SPM8 + Anatomy Beamforming DEM FieldMap MEEGtools conn vbm8 wfupickatlas
Matlab v.2013b
Warning: Contents.m overloaded by version in folder /Users/Michael/Documents/MATLAB/spm8/toolbox/vbm8