We have had many registrations recently that have been potentially malicious. These have mainly fallen in to two groups: the emails addresses from each group being from the same domain. After investigating the associated websites it was decided that these accounts (over 400) should be deleted and email domain blacklisted.
It is possible that valid accounts may have been deleted in error and, if so, we apologise. If this has happened please email us at firstname.lastname@example.org. It is not our intention to stop any genuine user from accessing the resources of this site.