Sounds like you have a virus on your system. If you have a button named "start" in the corner of your screen, then you have the Windows virus. Any HDD tainted by this should be quarantined from any other computers. Another virus that should be treated similarly is called Outlook.
These viri spread not through networks or other electronic data medium, but through humans. Somhow these viri infect people, who then willingly install them on their PCs, this is the only way they reproduce and in the reproduction somtimes money grows in Redmond, WA.
Remember, only YOU can prevent Windows.
