If the window was created by the calling thread, SendNotifyMessage calls the window procedure for the window and does not return until the window procedure has processed the message. If the window was created by a different thread, SendNotifyMessage passes the message to the window procedure and returns immediately; it does not wait for the window procedure to finish processing the message.
The SendMessage member function calls the window procedure directly and does not return until that window procedure has processed the message. This is in contrast to the PostMessage member function, which places the message into the window's message queue and returns immediately.
Messages in a message queue are retrieved by calls to the GetMessage or PeekMessage Windows function.
The Windows PostMessage function can be used to access another application.
以上SendNotifyMessage 、SendMessage和PostMessage 的MSDN描述，想必soloist (独行独奏) 已经看过了，我想你问的问题主要是为什么在98和2000下面会区别吧---我也很奇怪，但是我的代码中好像没有你说的问题啊，工作的很好，你仔细看看是不是你的机器上有其他的一些程序导致这样的后果？或者你的代码还有缺陷？