[Steve]

A malicious Facebook application which generates misleading messages to a
user's contact group in the social networking system is reported to have
spread to many users over the weekend just past; the application appears to
have done no actual harm, beyond creating messages that the user did not
want to send, but it is believed that it may be part of an indirect attempt
to attract internet users towards websites promoting scareware packages.

The application was called 'Error Check System', and posed as giving a
notification of errors in a Facebook user's profile. Anyone attempting to
view these pretended errors caused the application to start up, allowing it
to access to the affected user's friends, who were then spammed with
similar notifications, further spreading the social networking
chain-letter.

Facebook staff report that the application created a message 'blizzard'
over the weekend.

There are useful insights and advice, including examples, on the two Sophos
articles linked below, including reference to a fake Google search result
which would have potentially compounded the impression that your PC was
infected with malicious software and proposing software which claimed to
cleaning it up.

CNet: Facebook users targeted by rogue application | Security - CNET News
Sophos: Beware “Error Check System� Facebook application | Graham Cluley's blog
Sophos:A sting in the tail of the “Error Check System� Facebook scare | Graham Cluley's blog