I have read this thread: http://forums.malwarebytes.org/index.php?showtopic=62653 that also asks the same question as I have: This is what NOD32 is showing me <COLUMN NAME="Scanner">Startup scanner</COLUMN> <COLUMN NAME="Object">boot sector</COLUMN> <COLUMN NAME="Name">MBR sector of the 0. physical disk</COLUMN> <COLUMN NAME="Threat">probably unknown TSR.BOOT virus</COLUMN> <COLUMN NAME="Action">unable to clean</COLUMN> I am very worried about this as I have some very important word documents on my computer, is this a serious virus and what shall I do to protect my work? Kind regards.