If you have any more problems try this click here
There is a legacy "messenger" in Windows (I am asuming you have XP as you mention security centre)
which was used by administrators in large office networks.There is a basic security flaw that allows
spammers in.The above small download will safely make the necessary registry change to turn it off (and back on again should you ever need it). This is not the same as Windows Messenger used for MSN.