(1)Goto [start]->[run], type "msconfig" click "OK"
(2)Goto HKEY_LOCAL_MACHINE key
(3)Select "SOFTWARE" key
(4)Select "MiCROSOFT" key
(5)Select "WINDOWS" key
(6)Select "CurrentVersion" key
(7)Select "RUN" key
(8) Find the key which is releated the software you just downloaded and delete this key.