how do i get rid of a possible virus from my bt yahoo mail page?

Can anyone help me to get rid of an unknown and unwanted intruder from my Bt Yahoo mailbox ?

Ihave IE windows 7 on my pc .

In the menu section on the left of the screen in my email page it says Inbox, Conversations Drafts etc. but directly above that it says Compose message

and directly above that on the horizontal menu are boxes that say What's new,Inbox,Contacts.

Every day and all day for the past six weeks I have been getting a flashing box which appears across the horizontal menu tabs above, next to the 'Contacts' box which says nullebayc4862 and denotes a 'conversation' is going on although I do not know who nullebayc4862

is -also in the tab at the top of the page it says,'nullebayc4862 has sent you a new message'I and have to click a few x boxes to delete it , clicking the first x opens a conversation box with the words nullebayc4862 across the top -the box is empty and I

have never written anything to nullebayc4862 It says "you have been disconnected from Messenger"so i just click on the x to get rid of it and then click on the x which appears on the flashing box on the horizontal menu tabs above where it says nullebayc4862

. The message then goes away- only to return again 10 minutes later -it is so annoying .

What is it and how do I get it off my computer?

View this thread