...windows of the virus sender? there was this unknown chatter who is sending me i.m.'s which do multiple displaying of the same windows in my screen. once i closed one, more windows of the same sender appears..this person really disturbes me specially during time of my duty.

Typical yahoo booter program. You need to set multiple messages to appear in a single window in preferences. Then ignore anyone who is not on your messenger list and do not save any messages to archive.