RTHDCPL.EXE – Illegal System DLL Relocation

If you’re here looking for ways of how to fix this RTHDCPL.EXE – Illegal System DLL Relocation error, you’ve come to the right place.

Here are the symptoms of the problem and how to fix it from Microsoft Support website:

Symptoms of the problem
Certain programs may not start after you install security update 925902 (MS07-017) and security update 928843 (MS07-008) on a computer that is running Microsoft Windows XP with Service Pack 2 (SP2). Additionally, you may receive an error message that resembles the following:
application_executable_name – 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.

To resolve this problem, follow these steps:
1. Install all important updates here.

2. Try to run the program that did not start again. If the program starts and if you do not receive the error message in the “Symptoms of the problem” section, you are finished. If the error continues, follow steps 3 through 5.

3. Visit this website.

4. Click Download, and then click Run. If the Download button is not available, you must first click Validate to validate your copy of Windows.

5. Follow the instructions that appear on the screen to install update 935448.

For more information regarding this illegal system DLL relocation, click here.