A while ago, I wrote about Spammers using Skype to send unsuspecting users messages that their "copy of Windows needed updating", only to be taken to a page promoting a rogue antispyware tool.

Well, it looks like they've returned, ditching their old usernames (security.monitor.noXX) in favour of

(security.monitor.njXX)

As you can see, there are currently 21 of these accounts in Skype User Search. Do yourself a favour and ignore any messages from these accounts.