Reinstall windows default boot loader
Boot from Windows 7 installation CD:
Click Repair your computer > click Troubleshoot > click Advanced options > choose Command Prompt
bootrec /fixmbr
bootrec /fixboot
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Boot from Windows 7 installation CD:
Click Repair your computer > click Troubleshoot > click Advanced options > choose Command Prompt
bootrec /fixmbr
bootrec /fixboot