Today Kaspersky detected Windows\WinSxS\x86\_?

The one that Kaspersky is a vulnerability. Use Windows Update, as it will automatically update MSXML 4.0, or you can just go to Window's Update Site. If you use Vista, just run Automatic updates, if you use XP, use IE go the Windows Update Site (you can google it), and download updates there, as i find it easier and faster to download updates in IE.