Invalid Boot.ini file booting from C:\windows or Windows could not start error messages when you start your computer

A corrupted Boot file will not allow the computer to boot the operating system.This issue may occur if the Boot.ini file is missing,damaged, or contains incorrect entries. Also an invalid boot.ini file error is shown stating that the ntoskenl.exe file is corrupt or missing. The issue could be due to bad hardware as well. A defective RAM may also be responsible for the issue. However, if the RAM is fine and the Ntoskrnl.exe is missing or corrupt, the boot.ini will have to be repaired. It can be repaired manually by copying a correct version of the file in the directory or by using the Bootcfg utility from the Recovery Console for rebuilding the boot.ini file.

To resolve this issue, start the computer from the Windows XP CD, start the Recovery Console, and then use the Bootcfg.exe tool to rebuild the Boot.ini file. To do this, follow these steps:

1. Configure the computer to start from the CD-ROM or DVD-ROM drive. For information about how to do this, see your computer documentation, or contact your computer manufacturer.
2. Insert the Windows XP CD-ROM into your CD-ROM or DVD-ROM drive, and then restart your computer.
3. When you receive the "Press any key to boot from CD" message,press a key to start your computer from the Windows XP CD-ROM.
4. When you receive the "Welcome to Setup" message, press R to start the Recovery Console.
5. If you have a dual-boot or multiple-boot computer, select the installation that you have to use from the Recovery Console.
6. When you are prompted, type the administrator password, and then press ENTER.
7. At the command prompt, type bootcfg /list, and then press ENTER. The entries in your current Boot.ini file appear on the screen.
8. At the command prompt, type bootcfg /rebuild, and then press ENTER. This command scans the hard disks of the computer for Windows XP, Microsoft Windows 2000, or Microsoft Windows NT installations, and then displays the results. Follow the instructions that appear on the screen to add the Windows installations to the Boot.ini file. For example, follow these steps to add a Windows XP installation to the Boot.ini file:
   1. When you receive a message that is similar to the following message, press Y:
      Total Identified Windows Installs: 1
      [1] C:\Windows
      Add installation to boot list? (Yes/No/All)
   2. You receive a message that is similar to the following message:
      Enter Load Identifier
      Thisis the name of the operating system. When you receive this message, type the name of your operating system, and then press ENTER. This is either Microsoft Windows XP Professional or Microsoft Windows XP Home Edition.
   3. You receive a message that is similar to the following:
      Enter OS Load options
      When you receive this message, type /fastdetect, and then press ENTER.
      
      Note The instructions that appear on your screen may be different, depending on the configuration of your computer.
9. Type exit,and then press ENTER to quit Recovery Console. Your computer restarts, and the updated boot list appears when you receive the "Please select the operating system to start" message.

If this solution not work then use the following method

1. C:\Windows>cd system32 Press the Enter Key
2. C:\Windows\system32>del ntoskrnl.exe Press the Enter Key
3. C:\Windows\system32>copy d:\i386\ntoskrnl.ex_ Press the Enter Key
4. C:\Windows\system32>rename ntoskrnl.ex_ ntoskrnl.exe Press the EnterKey
5. C:\Windows\system32>exit Press the Enter Key and restart your PC.

Note  Replace [ d: ] by the letter corresponding to your CD-Rom drive.