Try the freeware programs first, such as Avast, Avira, or AVG.
If that doesn't work, then invest in a virus murder-death-kill program like Kaspersky or NOD32.
If that doesn't work, it's time to reformat.
If that doesn't work, then invest in a virus murder-death-kill program like Kaspersky or NOD32.
If that doesn't work, it's time to reformat.