u seem 2 have been attacked by a piece of malicious code
run a good anti-* scan 2 remove it
givin only free soln
Anti-virus AVAST [shud solve ur problem]
Anti-spyware Spybot [4 future attacks of spywares]
Anti-adware AD-AWARE SE PE [4 future attack from adwares]
dont gforget 2 kkep d defn upd8