Internet users should be careful when using Microsoft MSN Messenger as is being targeted by a new worm, security experts warn.
BlackAngel.B spreads via Microsoft IM, sending the following messages to all Messenger contacts: 'jaja look a that fantasma.zip' or 'mira este video fantasma.zip jaja'.
According to antivirus company Panda Software, the worm attempts to disable the security programs installed onto the computer, such as antivirus and firewalls.
It also prevents computer users from accessing certain operating system tools such as the Task Manager and the Registry Editor.
Security experts urge MSN Messenger users to not click on the link, which is included in the infected message as the executable file that looks like a Windows Media Player file compressed in ZIP format.
Yahoo email users have been also targeted by a different worm that exploited a javascript flaw in the system to infect users of Yahoo's email and webgroup services.
Graham Cluley, senior technology consultant for Sophos, said: "The good news is that Yahoo appears to have already fixed the problem, meaning that the Yamann worm can no longer spread via its systems."