>>Still, fdisk /mbr may still work as it did before. After rebooting again, rescan and see if it's still there. Then check whether everything else works.
>
>I tried your FDisk suggestion This message appears - BootSector Write! Virus: Continue (Y/N)
>The message blinks

Nice. So something in your machine is now aware of a request to write to boot sector. Where was it when you got the virus? Or is this the virus itself, trying to fool you?

Now if you are sure that you have typed the fdisk command all by yourself(*), you may continue.

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The airport security question of the same sort (did you pack your bags yourself ) would probably get me in trouble if I answered it faithfully - my wife packs my stuff. She somehow knows better than I do what do I need on a trip. I'm actually OK that I have to worry only about the hardware (laptop, camera, music, periphernalia)... but now, knowing that they'll ask me that stupid question ("no, I have packed the bags somebody elseself"), I make a point of going through the bag once before leaving and adding any stupid small item, so I can truthfully say "yes".