I recently came across a laptop which wouldn't boot into Windows. It continually complained about a missing or corrupt HAL.dll file. I've come across similar problems with corrupt or missing Windows system files so figured there would be a similar solution. A quick Google search found me exactly what I needed to know:
1. Boot a Windows XP installation CD and enter the Recovery Console.
2. Type expand d:\i386\hal.dl_ c:\windows\system32 (where d: is your CD drive and C: is your Windows installation - change as appropriate)
3. If you're asked to overwrite press 'Y'
4. Type 'Exit' to reboot
And that's all there is to fixing this issue. Hopefully that should solve the problem.
