Windows XP include a feature called Windows File Protection (WFP), part of the System File Checker, which is intended to avoid some of the common DLL consistency issues. This feature may also block valid attempts to change system files and it can therefore be disabled using this tweak.
NOTE: You will need your Windows XP CD-Rom and a hex editor to perform this tip. If you do not have a hex editor, we recommend using BinEdit, which is Freeware.
Step 1 1. Click on the Start button and select Run 2. Type in "regedit" and click OK 3. Look for this string: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\ Winlogon 4. In the right pane right-click on the "SFCDisable" string 5. Select Modify and type in "ffffff9d" in the Value Data box 6. Click OK and exit regedit Step 2 1. Go to C:\Windows\System32 2. Look for the "SFC_OS.dll" file 3. Right-click on the file and select "Copy" 4. Right-click on your Desktop and select "Paste" 5. Rename the new file to "SFC_OS1.dll" 6. Drag and drop the new file into the C:\Windows\System32 folder 7. Start up your hex editor and open the SFC_OS1.dll file 8. Click on Edit and select "Write Mode Enabled" 9. On the left side look for "0000e2b0" 10. This line contains the 8B and C6 bytes 11. Change these bytes to read 90 and 90 12. Click on the Save button and exit the hex editor Step 3 1. Insert your Windows XP CD-Rom 2. Shut down and restart your computer 3. At the prompt, hit any key on your keyboard to start your computer with the CD-Rom 4. Wait for the CD to load Windows 5. Press the R button on your keyboard to start the Windows XP Recovery Console 6. Follow the prompts on the screen 7. Now type in the following line exactly as it appears: copy C:\Windows\System32\sfc_os1.dll C:\Windows\System32\sfc_os.dll 8. Press Enter (type in Yes if asked to overwrite the file) 9. Remove the Windows XP CD-Rom 10. Type in Exit and press Enter to exit the Recovery Console