windows 7 stuck loading

My windows 7 has recently stopped working completely.
It hangs on the starting windows screen and the animation continues for hours.

I have tried so far unsuccessfully;
- safemode - didnt load
- last known config - didnt load
- using the Win 7 dvd - tried boot menu - boot from cd and then it just went back to starting windows normally again and froze.
- using a Win 7 repair disk - didnt boot as before
- unplugged all usb inputs - same result
- unplugged all hard drives other than main - same
- tried ram test / unplugged each ram - same
- removed power from wall.. held down power button on pc
- removed main hard drive and tried booting from Win 7 cd still nothing


Anything else I can do? I cant even do a clean install without the main hard drive in, if that is the problem.

I'm out of ideas.