Facebook members have been warned to be very careful with messages seemingly sent by friends.
This is because the Koobface worm, malware that attempts to infect your PC and turn it into a spam-producing 'bot', has stuck again.
Koobface sends out messages to all of the friends of a Facebook member inviting them to watch a video or something similar.
It was first spotted in the summer and to spread it relies on the friend opening the message and clicking on the link within.
This takes you to a video player that won't work unless you install an additional component, a message tells you. However, if you click on Install then you'll actually be installing a worm on your PC.
Facebook recommends that anyone infected with the worm should visit an online antivirus scanning site, such as those provided by Symantec, McAfee, BitDefender and Panda.
www.facebook.com/security