According to reports one user suffered her worst epileptic attack in 12 months when she clicked on an offending post at an Epilepsy Foundation site forum. Confronted by a full screen of rapidly flashing squares in different colours she quickly "locked up" and was rescued by the quick thinking of her 11 year old son who killed the browser process and prevented a full fit from occurring.
The non-profit organisation responded admirably quickly and closed the site briefly on Sunday in order to purge the forums of the messages, and hopefully patch the security holes which allowed them to be posted in the first place.
Wired claims that the attack was perpetrated by members of the informal griefer collective known as Anonymous, perhaps best known for its recent attacks on Church of Scientology sites. The report suggests that it might have been intended to generate anger towards a web site much disliked by its members, and which was referenced in the first batch of postings. It goes on to claim that some forum members had tracked down a now deleted forum thread planning the attack at a site known to be a stronghold of the group.