If I type the name Morgan in to the subject name the file name changes correctly but when I hit start ML freezes. Any ideas? Name has been used previously in the YYYYMODATTTTsubjectname.mat format. I can type a zero for the o in Morgan and it works fine. Current version of ML 2021b v3 Matlab. Is there a corrupt file I can up date?

I do not think it has anything to do with NIMH ML. Please check if your task code doesn't do something with the subject name.