d3dx9_40.dll 相关的错误可能源于多种不同原因。比如，错误的应用程序、 d3dx9_40.dll 被删除或放错位置、被您 PC 上存在的恶意软件破坏、损坏的 Windows 注册表等。
- 程序无法启动，因为您的计算机缺少 d3dx9_40.dll 。尝试重新安装程序来解决这个问题。
- 启动 d3dx9_40.dll 发生错误。无法找到指定的模块
- 加载 d3dx9_40.dll 发生错误。无法找到指定的模块
- d3dx9_40.dll 的设计可能不适合在 Windows 上运行，或可能包含错误。
在绝大多数情况下，解决方案是在您的 PC 上正确地重新安装 d3dx9_40.dll 到 Windows 系统文件夹。 此外，有的程序，特别是 PC 游戏，要求 DLL 文件放置在游戏/应用程序安装文件夹。
获取详细安装指南，请查看我们的 FAQ 。
关于 d3dx9_40.dll 的其他信息：
D3dx9_40.dll related errors are common while trying to run applications that require “Microsoft DirectX” to be displayed properly. Most errors are caused while trying to run games because games are the most frequent applications that require “Microsoft DirectX”. Other applications that utilize “Microsoft DirectX” are advanced graphic applications such as AutoCAD.
D3dx9_40.dll errors are associated with problems with “Microsoft DirectX” due to the fact that D3dx9_40.dll is one of many files that are required to function and to be in its right place, in order for “Microsoft DirectX” to work properly.
By downloading and reinstall the D3dx9_40.dll-file you can solve your problems that are caused by the malfunctioning file. Most of Microsoft “Windows” operating systems could be affected by an error caused by D3dx9_40.dll and the universal solution is to download a new D3dx9_40.dll-file.
If it for some reason doesn't work by just replacing the file, you might need to reinstall DirectX 9. You can find that on the microsoft.com website