Teachers report to me that some students cannot create a new account. When they attempt to create a new user, they receive an invalid login message. When I check Edit User Accounts and search for that username the student was attempting to create, we are told that no such user name exists. I also notice that there a several hundred nameless ghost accounts in my user database, growing at a rate of 50 per week or so. Last week I manually deleted 170 of such ghost accounts one by one. I speculate that students are partially creating a new account, somehow exiting, and then trying to create the account again. It appears this happens at a rate of 1 in 40 students. If you have never had this kind of report, then I wonder if there is something to do with Japanese keyboards and students switching between English and Japanese charsets. At any rate, Moodle is creating these blank accounts, reports no such user exists, yet a partial ghost user account seems to block the creation of anyone trying create an account using that username (in our case, we use their official student numbers as usernames).