A trick on Digital Unix machine if you know where your crash will create a core file is to create an empty core file (or empty the previous one by "/dev/null >core" ) before you fire Ansys and change the security by "chmod 000 core" so that the empty core file is now unwritable. This way if Ansys crash it will not fill (most of the time but not always...don't ask me why ;), the core file.