If you get an error regarding a missing or corrupt hal.dll file, it might simply be the BOOT.INI file on the root of the C: drive that is misconfigured
Insert and boot from your WindowsXP CD.
At the first R=Repair option, press the R key
Press the number that corresponds to the correct location for the installation of Windows you want to repair.Typically this will be #1
Type bootcfg /list to show the current entries in the BOOT.INI file
Type bootcfg /rebuild to repair it
Take out the CD ROM and type exit
In case you need to edit boot.ini
1. Right-click My Computer, and then click Properties.
-or- Click Start, click Run, type sysdm.cpl, and then click OK.
2. On the Advanced tab, click Settings under Startup and Recovery.
3. Under System Startup, click Edit.