Press the NumLock key to see whether the indicator light toggles on and off. If it's not working, this dysfunction indicates that the startup process is stuck at the BIOS phase. If there are any external peripherals connected to the computer, disconnect them.Ĭheck whether the hard disk drive light on the physical computer is working. To determine whether the system has passed the BIOS phase, follow these steps: If the computer repeatedly boots to the recovery options, run the following command at a command prompt to break the cycle:īcdedit /set bootmenupolicy legacy BIOS phase This article provides troubleshooting techniques for problems that occur during the first three phases. Select the thumbnail to view it larger.Įach phase has a different approach to troubleshooting. Before you start troubleshooting, you have to understand the outline of the boot process and display status to ensure that the issue is properly identified at the beginning of the engagement. Here's a summary of the boot sequence, what will be seen on the display, and typical boot problems at that point in the sequence. The kernel passes control to the session manager process (Smss.exe) which initializes the system session, and loads and starts the devices and drivers that aren't marked BOOT_START. Windows NT OS Kernel: The kernel loads into memory the system registry hive and other drivers that are marked as BOOT_START. Windows operating system loader: Essential drivers required to start the Windows kernel are loaded and the kernel starts to run. Windows Boot Manager: Windows Boot Manager finds and starts the Windows loader (Winload.exe) on the Windows boot partition. Firmware reads the master boot record (MBR), and then starts Windows Boot Manager. This pre-boot process ends when a valid system disk is detected.

PreBoot: The PC's firmware initiates a power-on self test (POST) and loads firmware settings. To troubleshoot boot problems, first determine in which of the following phases the computer gets stuck: Phase There are several reasons why a Windows-based computer may have problems during startup. If you're looking for more general information about recovery options, see Recovery options in Windows 10. This article is intended for use by support agents and IT professionals.

Corrupted registry