This can happen suddenly and without any visible cause. Sometimes your computer loads well and other times it time stops responding dduring start up process. This problem can be caused by many factors.
Sometimes, your computer will try to boot from the removable media you have plugged in. When it does that, you’re operating system will not load and your computer will fail to start up as expected. Check and remove any CD’s, DVD’s, USB flash drives and memory cards. Remove any digital cameras or external hard drives. Try to restart your computer. If your desktop displays an error during start up, this is probably caused by a hardware configuration problem. Your motherboard, CPU, memory or graphic card may have developed an issue.