Message: the error handling method of ActiveX control cannot be instantiated because the current thread is not in a single thread unit.

Recently, I was working on a simple Screen Saver. The function was very simple, that is, to start a screen saver at a certain interval when the machine was not used for a long time. I want to play some media files (. Avi,. wmv) and Flash files. Therefore, I use Windows mediaplayer as the player.
For some special reasons, I need to start the screen saver in a program without a GUI, so the system. threading. timer is used as the timer, but it is found that the following exceptions are always present during the test:
Message: because the current thread is not in a single thread unit, the ActiveX Control "6bf52a52-394a-11d3-b153-00c04f79faa6" cannot be instantiated ".
Source: system. Windows. Forms
At system. Windows. Forms. axhost .. ctor (string CLSID, int32 flags)
At system. Windows. Forms. axhost .. ctor (string CLSID)
At axwmplib. axwindowsmediaplayer .. ctor ()
...
After a long time, I found that the original windowsmediaplayer control can only be run in a single-threaded environment. Later I changed my timer to system. windows. forms. timer object, and then test. Everything is OK! Conclusion: I found that I did not read the development documents of Ms well when I was writing some programs through this error. I did not pay attention to thread security. I should pay special attention to this issue during the next development.