File is missing or corrupt.....system32\ntoskrnl.exe

Hello, and welcome to Geeks To Go.
If you have your Windows XP disk

Insert your Windows XP disk into your computer and reboot
Make sure the PC is set to run from the CD as the primary boot device.
NOTE: You do this by setting your PC to boot to the CD-ROM in BIOS (enter bios by pressing f1, f2 or del key during memory count up, then search for boot order, and set the CD as the first boot device)
When the PC boots, it will boot from the CD...after the first several screens load, you will be given a choice to choose R for Recovery Console. You will be asked to log in.
NOTE: For Windows XP Home, there is not password, just hit ENTER. For Windows XP pro, ask whomever set up the machine what password they used.

When you see the Recovery console C:\WINDOWS prompt continue to section 3 (Running "ChkDsk")

If you DO NOT have your Windows XP disk

Download RC.ISO from Here.
Now burn this ISO image to a CD and boot your computer with it.
NOTE: Keep in mind that this is different than burning a file to a CD-ROM. If you do not know how to burn an ISO image, then download CDBurnerXP Pro to another Windows machine and install it. Then go Here for instructions for burning the ISO image
Once the CD is created, place it in the defunct computer
Then reboot your broken PC with that CD in the CD-ROM drive.
Make sure the PC is set to run from the CD as the primary boot device.
NOTE: You do this by setting your PC to boot to the CD-ROM in BIOS (enter bios by pressing f1, f2 or del key during memory count up, then search for boot order, and set the CD as the first boot device)
When the PC boots, it will boot from the CD...after the first several screens load, you will be given a choice to choose R for Recovery Console. You will be asked to log in.
NOTE: For Windows XP Home, there is not password, just hit ENTER. For Windows XP pro, ask whomever set up the machine what password they used.

Running "ChkDsk"

At the Recovery console C:\WINDOWS prompt, type

chkdsk /r
Press ENTER
Let this scan run UNINTERUPTED untill completed (30 min or so depending on the drive)
Report any errors in your next reply
Once the scan is complete, Type exit, and then press ENTER to quit Recovery Console.
Your computer will now restart, boot from the CD again and continue with the next steps.

Using "BootCfg /Rebuild" to fix the "Boot.ini" file

At the Recovery console C:\WINDOWS prompt, type

bootcfg /rebuild
Press ENTER
Note:The bootcfg /rebuild command scans the hard disks of the computer for Windows NT 4.0, Windows 2000, or Windows XP installations, and then displays the results. You can add the detected Windows installations.
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)

NOTE: You may see more than one entry here if you have a dual boot windows system. If this is the case follow this procedure for ALL installations to make sure that all OS's are added correctly
You receive a message that is similar to the following message:

Enter Load Identifier
NOTE:This is the name of the operating system. This is either Microsoft Windows XP Professional or Microsoft Windows XP Home Edition.
Type the name of your operating system, and then press ENTER
You receive a message that is similar to the following:

Enter OS Load options
Type /fastdetect, and then press ENTER.
Type exit, and then press ENTER to quit Recovery Console.
Your computer will restart, and the updated boot list may apear when you receive the "Please select the operating system to start" message.
If you see a Boot list with multiple entries choose the XP Home option to boot to windows.