After you install the security update update KB925902 (MS07-017) and security update KB928843 (MS07-008) on a Windows XP Service Pack 2 (SP2)-based computer, Realtek HD Audio Control Panel (Rthdcpl.exe) may not start. Additionally, you receive an error message that is similar to the following:
Rthdcpl.exe – Illegal System DLL Relocation The system DLL user32.dll was relocated in memory. The application will not run properly. The relocation occurred because the DLL C:\Windows\System32\Hhctrl.ocx occupied an address range reserved for Windows system DLLs. The vendor supplying the DLL should be contacted for a new DLL.
How to resolve
Install the following update for Windows XP (KB935448), this will resolve the issue where the Realtek HD Audio Control Panel may not start after you install security update KB925902 (MS07-017) and security update KB928843 (MS07-008).