Method 1: Disconnect all the devices connected to the computer except keyboard and mouse and check if you are able to boot to the start screen. Method 2: If the computer fails to boot, try performing safe mode and perform clean boot. Try to boot into Safe Mode with Networking. Press and hold the　shift key　while clicking on　Restart　at the login Screen (Bottom right corner). •Select Troubleshootand click on　Advanced Options. •Select　Startup Settingsand click on Restart. •After restarting, choose　Enable Safe modewith networking. If the issue does not persists in Safe Mode, then perform a Clean Boot to check if any third party application is causing the issue, as Clean Boot helps in eliminating software conflicts. Step 2 Put the computer in Clean Boot and check if it helps. By setting your system in Clean Boot state helps in identifying if any third party applications or startup items are causing the issue. How to perform a Clean Boot to troubleshoot a problem in Windows Vista, Windows 7, or Windows 8...