engine - 3:42 pm on Nov 28, 2012 (gmt 0)
Facebook says it is investigating a fault which has seen some of its members re-registered to groups that they had quit.
One administrator of "secret" groups on the network raised concerns that old members would be able to access "highly sensitive" information.
Others have complained of having to leave the groups, one-by-one, again.
Facebook Investigating Group Membership Re-Registration Glitch [bbc.co.uk]