Thank you for your post.
Does this occur with every file, or just the current file? That is, if you create a new database file, go to File -> Manage -> Security..., add an account, do you also get a crash?
If you create a clone of the file (a copy with no records), are you able to add an account?
If only this file is damaged, then run a recover on the clone, and import the data from the original file. Ideally, revert to a backup file and import the data from the original file.
Keep me posted with any progress.