Windows XP won't start

Resolution

1. Restart the PC. The hal.dll error could be a fluke.
   
   
2. Check for proper boot order in BIOS. You might see the hal.dll error if the boot order in BIOS is first looking at a hard drive other than your main hard drive.
   
   Note: If you've recently changed your boot order or recently flashed your BIOS, this may be what's causing your problem.
   
   
3. Run Windows XP System Restore from a command prompt. If this doesn't work or you're receiving the hal.dll error message before you're able to complete this process, move on to the next step.
   
   
4. Repair or replace the boot.ini file. This will work if the cause of the problem is actually Windows XP's boot.ini file and not the hal.dll file, which is often times the case.
   
   Note: If repairing the boot.ini does correct the hal.dll issue but the problem reappears after a reboot and you've recently installed Internet Explorer 8 in Windows XP, uninstall IE8. In this specific situation, IE8 could be the root cause of your hal.dll problem.
   
   
5. Write a new partition boot sector to the Windows XP system partition. If the partition boot sector has become corrupt or isn't properly configured, you may receive the hal.dll error.
   
   
6. Recover data from any bad sectors on your hard drive. If the physical part of your hard drive that stores any part of the hal.dll file has been damaged, you're likely to see errors like this.
   
   
7. Restore the hal.dll file from the Windows XP CD. If the hal.dll file is truly the cause of the problem, restoring it from the original Windows XP CD may do the trick.
   
   
8. Perform a repair installation of Windows XP. This type of installation should replace any missing or corrupt files. Continue troubleshooting if this does not resolve the issue.
   
   
9. Perform a clean installation of Windows XP. This type of installation will completely remove Windows XP from your PC and install it again from scratch.
   
   Note: While this will almost certainly resolve any hal.dll errors, it is a time consuming process due to the fact that all of your data must be backed up and then later restored.
   
   Important: If you can't gain access to your files to back them up, understand that you will lose them all if you continue with a clean installation of Windows XP.
   
   
10. Test the hard drive. If all else has failed, including the clean installation from the last step, you're most likely facing a hardware issue with your hard drive but you'll want to test it to be sure.
    
    If the drive fails any of your tests, replace the hard drive and then install a new copy of Windows XP.

For that you need winxp bootabler disk.
Tehn boot your computer with tht and go to recoverry console.
Then type in command prompt "chkdsk /r"
then press "y"
then it fixc error on harddisk.
Then after completing it restart your computer and boot with harddisk then it ok.

Follow this link
http://www.kellys-korner-xp.com/xp_haldll_missing.htm