*THIS FIX WILL REMOVE ALL DATA FROM YOUR HARD DRIVE. BACKUP YOUR INFORMATION WHERE POSSIBLE*
To everyone having this problem I have a solution for you that worked perfectly. It took me a little bit to find the right way to do it, and the best way possible is to
COMPLETELY WIPEyour hard-drive.
This will only work if you have an install disk, even if you cannot access your system, or log in, this will work.
First of all you want to put the Install disk in the tray (32Bit or 64Bit depending on your machine), then when prompted its should say "Press any key to boot from CD/Disk" or something along those lines.
Go through all the installation, put in your CD key, then when you get to a menu look for an option of "ADVANCED SETTINGS/OPTIONS". When you have found this, go to Command Prompt section. Once you have the command console open follow this guide:
http://www.techhack.co.uk/2011/03/31/format-a-hard-drive-with-command-prompt/
It will take you step by step through the process of how delete the information on your hard-drive which will include the corrupted OS.
Once you have that done, you then want to boot from CD again, input your CD key again, but this time it will prompt you to install rather than repair (because the OS has been wiped). The process from techhack may create the partition in a invalid format,
do not fear, when the OS installer pops up, just delete the partition that was created using the techhack tutorial and click "new", this will then ask if you would allow Windows to create partitions for you (these partitions include back-ups, external files,
etc). Then thats its, it should start to process your installation.
I'm sorry that this is a rather crude way of doing this, and it is a little complicated, but if you follow the techhack guide and what I have said allow you to get your PC back.
Hope this helps.
Disclaimer: I'm fairly fluent with this kind of stuff, so if you aren't comfortable with it, ask someone who knows about Partitions and the CMD prompt console.