Is this a Samsung computer? If it is, I would do one of three things.

1. Contact their tech support. It sounds like they do some pretty screwy things with partitioning and use the Linux bootloader to manage it all.

2. Download Kill Disk (the free version). Google around to learn how to use it. Totally remove everything from your hard drive. Then install Windows again starting with a truly clean slate.

3. Take your computer to a local computer tech guy and have him do something similar to number 2.

By the way, congrats on having everything backed up. Made your life much easier.