You can run windows and reinstall it. Since you have a restore disk, I presume you have some proprietary computer that doesn't have a Microsoft Windows install disk. Run the reinstall if the AV doesn't work. Folks who have the full install disk of Windows can run setup from within windows and rebuild most of the OS while keeping alltheir settings. Runing setup from a DOS prompt fixes more and still keeps most settings. format or fdisk is quite drastic. Backup before you do that. Don't feel bad, I had a room mate call me at work and ask what it means when the black screen comes up and says it can't find the MBR. In order to save the drive, I had to move the MBR to a different sector. Fdisk didn't help. Lost all the data too. Have no idea what he did.