There are already at least two other threads about this in this very forum about Yahoo: http://forum.avast.com/index.php?topic=74340.0 http://forum.avast.com/index.php?topic=74350.0
And at least another three about ads elsewhere: http://forum.avast.com/index.php?topic=74347.0 http://forum.avast.com/index.php?topic=74349.0 http://forum.avast.com/index.php?topic=74345.0
Please use search function before starting new thread. http://forum.avast.com/index.php?action=search