Microsoft will be releasing security patches today (after all, it's Tuesday!). One of these patches may require a hotfix on some Windows XP systems that use Realtek audio drivers.

After installing the patches and restarting your computer, the Realtek HD Audio Control Panel may not start, and an error message may display:

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.

The problem is that hhctrl.ocx and user32.dll files have conflicting base addresses.

Microsoft KB article 935448 links to a download that includes a hotfix for this.

Note: You must have Windows XP SP2 installed.