Then I would first do the BIOS update to see if that helps. If the BIOS update doesn't fix things, then you will need to do a fresh install.
Shove all your personal data onto the drive the OS won't be on, and then unplug it so no boot files will go onto the drive.
During the installation, when you're choosing the drive/partition, delete all the partitions just to clear the drive from the old install.
And once Windows is installed, install drivers, updates, etc...
You may need to call up Microsoft to activate Windows if your 7 keyis an OEM licence.