Where did you get Win7? The first suspect here is the ISO integrity or Burn. Confirm ISO or download another then burn to DVD using ImgBUrn at 4x speed, or write to flash stick using Universal USB Installer
with Win7 in dropdown, boot stick under USB, REmovable or HD although it should autostart on clean HD.
If your HD is used wipe it first of any possible boot sector corruption: SSD - HDD Optimize for Windows Reinstallation