I've been having user accounts disappear seemingly at random lately. One day someone can post, the next they can't. They'll request their password, and receive an email with nothing in the spaces for username and password. The corresponding usernumber.cgi file will be zero bytes, but they'll still exist in memberslist.cgi and emaillist.cgi (I checked my quotas, and I'm will below). If I do a member file recalibrate, they'll disappear from those files as well. With no way to get their profiles back, I'm just telling users to re-register. Of course then they lose their status and post totals, which makes some people mildly sad. And sad users are no fun.
Any idea what might be causing this? It's nwtekno.org, running 5.47a, stock, but I just upgraded to 5.47d a few minutes ago.