Solving Common Boot Problems “Part I”

This section describes problems that can occur during the boot process, describing their symptoms, causes, and approaches to solving them. To help you locate a problem that you might encounter, they are organized according to the place in the boot at which they occur. Note that for most of these problems, you should be able to simply boot into the Windows Recovery Environment and allow the Startup Repair tool to scan your system and perform any automated repair tasks.


MBR Corruption
• Symptoms A system that has Master Boot Record (MBR) corruption will execute the BIOS power-on self test (POST), display BIOS version information or OEM branding, switch to a black screen, and then hang. Depending on the type of corruption the MBR has experienced, you might see one of the following messages: “Invalid partition table,” “Error loading operating system,” or “Missing operating system.”

• Cause The MBR can become corrupt because of hard-disk errors, disk corruption as a result of a driver bug while Windows is running, or intentional scrambling as a result of a virus.

• Resolution Boot into the Windows Recovery Environment, choose the Command Prompt option, and then execute the bootrec /fixmbr command. This command replaces the executable code in the MBR.


Boot Sector Corruption
• Symptoms Boot sector corruption can look like MBR corruption, where the system hangs after BIOS POST at a black screen, or you might see the messages “A disk read error occurred,” “BOOTMGR is missing,” or “ BOOTMGR is compressed” displayed on a black screen.

• Cause The boot sector can become corrupt because of hard-disk errors, disk corruption as a result of a driver bug while Windows is running, or intentional scrambling as a result of a virus.

• Resolution Boot into the Windows Recovery Environment, choose the Command Prompt option, and then execute the bootrec /fixboot command. This command rewrites the boot sector of the volume that you specify. You should execute the command on both the system and boot volumes if they are different.


BCD Misconfiguration
• Symptom After BIOS POST, you’ll see a message that begins “Windows could not start because of a computer disk hardware configuration problem,” “Could not read from selected boot disk,” or “Check boot path and disk hardware.”

• Cause The BCD has been deleted, become corrupt, or no longer references the boot volume because the addition of a partition has changed the name of the volume.

• Resolution Boot into the Windows Recovery Environment, choose the Command Prompt option, and then execute the bootrec /scanos and bootrec /rebuildbcd commands.
These commands will scan each volume looking for Windows installations. When they discover an installation, they will ask you whether they should add it to the BCD as a boot option and what name should be displayed for the installation in the boot menu. For other kinds of BCD-related damage, you can also use Bcdedit.exe to perform tasks such as building a new BCD from scratch or cloning an existing good copy.


System File Corruption
• Symptoms There are several ways the corruption of system files—which include executables, drivers, or DLLs—can manifest. One way is with a message on a black screen after BIOS POST that says, “Windows could not start because the following file is missing or corrupt,” followed by the name of a file and a request to reinstall the file. Another way is with a blue screen crash during the boot with the text, “STOP: 0xC0000135 {Unable to Locate Component}.”

• Causes The volume on which a system file is located is corrupt or one or more system files have been deleted or become corrupt.

• Resolution Boot into the Windows Recovery Environment, choose the Command
Prompt option, and then execute the chkdsk command. Chkdsk will attempt to repair volume corruption. If Chkdsk does not report any problems, obtain a backup copy\ of the system file in question. One place to check is in the \Windows\winsxs\Backup directory, in which Windows places copies of many system files for access by Windows Resource Protection. (See the “Windows Resource Protection” sidebar.) If you cannot find a copy of the file there, see if you can locate a copy from another system in the network. Note that the backup file must be from the same service pack or hotfix as the file that you are replacing.

Source of Information : Microsoft Press Windows Internals 5th Edition