The Boot Process (XP)

Issues with the hard drive, drive cable, motherboard, or even memory can affect the boot and generate some of the following errors. Check all hardware before starting the software portion of this.

1) The MBR 
- scans partition table
- selects first active partition as the system volume
- loads boot sector from system volume
Symptoms: 
Hangs at black screen
Invalid Partition Table error message
Missing Operating System error message
Error Loading Operating System error message

How To Fix: Load Recovery Console and run "fixmbr" (5-15) (this discounts any disk/file system errors that can be ruled out with disk diagnostic and chkdsk)

2) The Boot Sector
- Reads root directory
- loads NTLDR
Symptoms: 
Black screen hang
Disk Read Error occurred
NTLDR missing/compressed

How To Fix: Load Recovery Console and run "fixboot" (5-17) (this discounts any disk/file system errors that can be ruled out with disk diagnostic and chkdsk)

3) NTLDR (Black Screen)
- moves system from 16 bit to 32 bit operation and enables paging
- accesses and reads SCSI devices if needed
Loads the file system driver (NTFS or FAT32) - SEE 13 LINES DOWN FOR IDENTICAL ENTRY
- reads BOOT.INI - displays boot menu (with timeout)
Symptoms: Boot Device is Inaccesible
How To Fix: Bootdfg /rebuild (5-20)
- moves CPU into 64 bit mode if a 64 bit installation is used
- F8 becomes available for special boot menu
- executes Ntdetect.com for hardware detection (saved later to HKLM\Hardware\Description)
- Loads: 
- HKLM\System hive
Symptoms: System Hive is Corrupt (5-23)
How To Fix: chkdsk /f /r
and/or replace from System Restore or C:\Windows\Repair
**Found bad cable causing this error x1
- boot drivers - critical for loading File System (FAT32 or NTFS) - SEE 13 LINES UP FOR IDENTICAL ENTRY
- Ntoskrnl.exe
Symptoms: File missing or corrupt (5-25)
How To Fix: chkdsk /f /r, then get copy from driver cache

- Hal.dll
Symptoms: File missing or corrupt (5-25)
How To Fix: chkdsk /f /r, then get copy from driver cache
- transfers control to Ntoskrnl.exe

4) NTOSKRNL.EXE (Splash screen shows up)
- initializes kernel
- I/O Manager starts Boot-Start drivers, then System-Start drivers
- creates Session Manager process (Smss.exe) - the first user-mode process
Symptoms: System Crash due to bad driver or corrupt registry hive
How To Fix: Last Known Good Configuration; Safe Mode; Recovery Console; PE mode

5) Smss.exe
- Runs BootExecute programs (things like autochk)
- Processes "delayed move/rename" commands (remove on reboot stuff)
- Initializes paging file and the rest of the registry hives
- Loads and initializes Win32k.sys (kernel mode part of Win32 subsystem)
- Starts Csrss.exe (user mode part of Win32 subsystem)
- Starts Winlogon.exe

6) Winlogon.exe
- Starts Lsass.exe
- Loads GINA to wait for logon
- Starts Services.exe

7) Services.exe
- Starts Win32 services marked as Automatic start (includes drivers marked as such)
- Is asynchronous to logon process

Presumes
- disk OK (mfr diagnostic)
- file system OK - (chkdsk)

-MBR error (fixmbr)
Hangs at black screen
Invalid Partition Table error message
Missing Operating System error message
Error Loading Operating System error message

- Boot Sector error (fixboot)
Black screen hang
Disk Read Error occurred
NTLDR missing/compressed

- NTLDR
Boot Device is Inaccesible (bootcfg /rebuild)
System Hive is Corrupt (restore system hive fm backup)
other File missing or corrupt (restore copy from backup

- NTOSKRNL.EXE (Splash screen shows)
System Crash due to bad driver or corrupt registry hive (LKG, Safe Mode, Recovery Console, PE mode - to replace driver or registry hive).

Black screen after this usually reflects video driver issues - check in Safe Mode.

Disk diagnostic and CHKDSK /F /R are common to all in order to rule out:
- physical disk problems and 
- file system problems PRIOR to trying the fix.

Common to several fixes
Black Screen Hang (before splash screen shows)
- Disk Diagnostic
- CHKDSK /F /R (try to boot)
- fixmbr (try to boot)
- fixboot (try to boot)
- Safe Mode (try to boot)

MBR
Invalid Partition Table
Missing Operating System
Error Loading Operating System
- Disk Diagnostic
- CHKDSK /F /R 
- fixmbr (try to boot)

BOOT SECTOR
Disk Read Error occurred
NTLDR missing/compressed ( http://tinyempire.com/notes/ntldrismissing.htm )
- Disk Diagnostic
- CHKDSK /F /R
- fixboot (try to boot)

NTLDR 
Boot Device is Inaccesible (boot.ini)
- Disk Diagnostic
- CHKDSK /F /R
- bootcfg /rebuild

System Hive is Corrupt
- Disk Diagnostic
- CHKDSK /F /R
- restore System Hive from backup

other File missing or corrupt
- Disk Diagnostic
- CHKDSK /F /R
- restore copy from backup

NTOSKRNL.EXE
Black Screen Hang (after splash screen appears) (usually video driver)
- Last Known Good Configuration
- Safe Mode