Text automatically getting copied in Excel Sheet from Web? (Malware?

Of late, I have noticed that whenever I am working in excel (with broadband connection on), following text automatically gets copied in one cell “unVao day nghe bai nay di ban a href="http://www.freewebtown.com/gaigoisaigon/" rel="nofollow"http://www.freewebtown.com/gaigoisaigon//a C:\WINDOWS\hinhem.scr……….www.freewebtown… I have a disturbing feeling that it is happening due to some spyware/malware. IHas anyone come across similar problem? What is it and how to stop it?