Problem with Hal.dll

Hi, im new here so i dont know if it in the right part of the forum.

Im having a problem with hal.dll in system32, im using win7 and i am trying to reinstall XP off a usb stick, and when i try load in txt mode it comes up with

"Windows could not start because the following file is missing or corrupt:
<Windows root>\system32\hal.dll.
Please re-install a copy of the above file."

Win7 boots up fine, but when i try "Expand" string it says access denied, i have tried changing my account to Trustedinstaller and still get the Access Denied error.

Any ideas how to fix this please?

Thanks in advance.