You could try one last thing before reinstalling: hold down the F8 key when you boot into Windows, until you get a screen that allows you to select the start-up mode. Try Safe Mode first and see if it boots up. If not, you will definitely need to reinstall. If it boots, let Windows sit and sort itself out for a few minutes and try a restart without F8. On occasion, this will correct the problem. Otherwise, a reinstall is probably a better use of your time.....