I have a [ComRegisterFunction] that I am using to register a BHO Internet explorer extension. During registration on 64-bit windows 7 machines, a UnauthorizedAccessException is thrown on the call to subKey.SetValue("NoExplorer", 1). The registry appears to have BHO's located @ \HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\explorer\Browser Helper Objects, however, I get them same exception when trying to register there. Any Help would be appreciated. [ComRegisterFunction] public static void RegisterBho(Type type) { string BhoKeyName= "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Browser Helper Objects"; RegistryKey registryKey = Registry.LocalMachine.OpenSubKey(BhoKeyName, true) ?? Registry.LocalMachine.CreateSubKey(BhoKeyName); if(registryKey == null) throw new ApplicationException("Unable to register Bho"); registryKey.Flush(); string guid = type.GUID.ToString("B"); RegistryKey subKey = registryKey.OpenSubKey(guid) ?? registryKey.CreateSubKey(guid); if (subKey == null) throw new ApplicationException("Unable to register Bho"); subKey.SetValue("NoExplorer", 1); registryKey.Close(); subKey.Close(); }