When upgrading from XP Home to XP Pro, or when Automatic Updates aren't working correctly, try this.

Batch file HERE (you must be logged in).

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