There are many ways but a favorite way is to boot any Linux LiveCD and to use the syslinux package like so: Just change the "sdx" to your sd for example /dev/sda or whatever the drive is that is supposed to boot Windows. sudo dd if=/usr/lib/syslinux/mbr/mbr.bin of=/dev/sdx 0+1 records in 0+1 records out 440 bytes copied, 0.0197808 s, 22.2 kB/s........

If the below is happening on KVM (a very weird and scary looking error) it's probably because of Windows. This has happened countless times to me where the bootsector on Windows 7/2008 becomes corrupted easily (even by a crash or shutdown). KVM: unknown exit, hardware reason 0x80000021 kvm_run returned -22 rax 0000000000000010 rbx 0000000000000080 rcx 0000000000000000 rdx 0000000000000080 rsi 000000000025db2a rdi 000000000007db2a rsp 0000000000000200 rbp........

This seems to be common for some reason when trying to run Windows 7 under KVM and 7 has always had strange issues with KVM. What happens for me is after the install it simply won't boot, it stays on the POST screen and does nothing. For some reason it appears the boot sector either doesn't get installed or gets corrupted with KVM. The solution is to boot the install disc for Windows 7 and reinstall the windows MBR into the boot sector: 1. Boot t........