1. Read the screen. The error could be something as simple as a power interruption during shut-down or startup. The screen itself will offer the chance to start Windows normally. This is already selected by default. Try it first by pressing the 'Enter' key on your keyboard. If it works, after Windows loads, shut it down again properly. Allow it to reboot.
2. Try another of the choices on the blue screen. If starting Windows normally doesn't work, try the option to use the last known good configuration. You will need to use the arrows on your keyboard to move the highlight bar to that option. After that choice is highlighted, press your 'Enter' key. If it works and you boot into Windows, shut down and restart the computer normally.

3. Choose to start in safe mode. If the other two choices don't work, use the arrow keys to select the option to start in safe mode. As before, if the computer boots into the selected option, shut down and restart.
4. Take drastic measures. This is chosen last because it will fully reset your computer. This option will restore the computer to its original factory settings and removes all files and programs that you have installed. To use this option, shut off the computer and turn it back on. Press the 'F10' key repeatedly while the computer is attempting to reboot. This triggers an MS DOS-based program that is in every version of Windows. This will restore your computer and eliminate the blue screen error.