My MSI custom action DLL (C++), using Windows Vista, can not read HKEY_LOCAL_MACHINE registry section. While it can read HKEY_CURRENT_USER keys fine. Note that the custom action DLL is working fine on Windows Server 2003.

Another interesting fact is that the DLL can read HKEY_LOCAL_MACHINE registry on Windows Vista, when it is loaded by an simple dialog based application (and not working for MSIEXEC.exe)

What am I missing? your help is highly appriciated.