Windows XP System File Repair

WINDOWS XP SYSTEM FILE CHECK

This describes System File Checker (Sfc.exe), which is a command-line utility used with the Windows File Protection (WFP) feature.

System File Checker gives an administrator the ability to scan all protected files to verify their versions. If System File Checker discovers that a protected file has been overwritten, it retrieves the correct version of the file from the cache folder (%Systemroot%\System32\Dllcache) or the Windows installation source files, and then replaces the incorrect file.

System File Checker also checks and repopulates the cache folder. You must be logged on as an administrator or as a member of the Administrators group to run System File Checker. If the cache folder becomes damaged or unusable, you can use the sfc /scannow, the sfc /scanonce, or the sfc /scanboot commands to repair its contents.

System File Checker Tool Syntax

Sfc [/Scannow] [/Scanonce] [/Scanboot] [/Revert] [/Purgecache] [/Cachesize=x]

• /Scannow: Scans all protected system files immediately and replaces incorrect versions with correct Microsoft versions. This command may require access to the Windows installation source files.

• /Scanonce: Scans all protected system files one time when you restart your computer. This command may require access to the Windows installation source files when you restart the computer. The SfcScan DWORD value is set to 2 in the following registry key when you run this command:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

• /Scanboot: Scans all protected system files every time you start your computer. This command may require access to the Windows installation source files every time you start your computer. The SfcScan DWORD value is set to 1 in the following registry key when you run this command:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

• /Revert: Returns scan to the default setting (do not scan protected files when you start the computer).The default cache size is not reset when you run this command. This command is equivalent to the /Enable switch in Windows 2000.

• /Purgecache: Purges the file cache and scans all protected system files immediately. This command may require access to the Windows installation source files.

• /Cachesize=x: Sets the file cache size to x megabytes (MB). The default size of the cache is 50 MB. This command requires you to restart the computer, and then run the /purgecache command to adjust the size of the on-disk cache. This command sets the SfcQuota DWORD value to x in the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

Fix For Windows Update

Windows Update will download files but won't Install them or produces errors.

Perform these steps

1. Click Start->Run, type "services.msc" (without quotation marks) in the open box and click OK.
2. Double click the service "Automatic Updates".
3. Click on the Log On tab, please ensure the option "Local System account" is selected and the option "Allow service to interact with desktop" is unchecked.

4. Check if this service has been enabled on the listed Hardware Profile. If not, please click the Enable button to enable it.
5. Click on the tab "General "; make sure the "Startup Type" is "Automatic". Then please click the button "Start" under "Service Status" to start the service.
6. Repeat the above steps with the other service: Background Intelligent Transfer Service (BITS)

Step 4: Re-register Windows Update components and Clear the corrupted Windows Update temp folder
================================

1. Click on Start and then click Run,
2. In the open field type "REGSVR32 WUAPI.DLL" (without quotation marks) and press Enter.
3. When you receive the "DllRegisterServer in WUAPI.DLL succeeded" message, click OK.
4. Please repeat these steps for each of the following commands:

REGSVR32 WUAUENG.DLL
REGSVR32 WUAUENG1.DLL
REGSVR32 ATL.DLL
REGSVR32 WUCLTUI.DLL
REGSVR32 WUPS.DLL
REGSVR32 WUPS2.DLL
REGSVR32 WUWEB.DLL

After the above steps are finished. Sicne temporary folder of Windows Update may be corrupted. We can refer to the following steps to rename this folder that

1. Click Start, Run, type: cmd and press Enter. Please run the following command in the opened window.

net stop WuAuServ