Humm, it should have removed the files from the server if they did that...
See, the login name is saved within every post, so the member file doens't need to be there; it'll show them as "unregistered" for their posts however...
What does your memberslist.cgi file look like? is it full, empty, etc?
Are your memberfiles in tact? Do they have 43 lines? (i think it's 43, too early)...