This can happen suddenly and without any visible cause. Sometimes your computer begins to load but after some time stops responding during start up process. This problem can be caused by many factors.
Your computer can try to load windows from removable media. First of all check and remove any CD’s, DVD’s, USB flash drives, memory cards. Remove any digital cameras or external hard drives. Try to restart your computer. If it fails again something else is causing the problem. If your desktop displays an error during start up, this is probably caused by a Windows update issue, driver conflict, malware or hardware configuration problem. Your motherboard, CPU, memory or graphic card may have developed a problem as well.