Is your computer mentioning something along the lines of needing to check the disks? Sometimes when you've turned the PC off without properly shutting-down Windows, it will want to check the disks before booting the Windows operating system.
You may see this happening on boot-up, with a percentage complete indicator on the screen. Let it do this - once complete it should boot Windows normally, assuming no disk errors have been found.
Always remember to try and shut Windows down properly - although I guess you may have had an issue here, either power failure, or your PC froze meaning you had to turn the power off.
Ross, February 2010
