Microsoft developed a number of DLL files specifically for handing tasks related to video and game programming. D3dx9_25.dll is one of the files used in the development of games for Windows, and Microsoft Xbox and Xbox 360.
D3dx9_25.dll is mainly used to govern 3D graphics, specifically with Microsoft's Direct-X compatible video processors. It is part of the Windows operating system and is used for displaying graphics, 3D animation and other multimedia, as well as audio and surround sound. The DLL file allows access to display cards and audio cards, and therefore is important to the correct running of your computer.
If you have a problem with d3dx9_25.dll, such as the file is missing, damaged or corrupt, you are likely to see a number of different error messages:
These windows file errors will usually manifest themselves when accessing an application that involved multimedia such as audio and 3D graphics. In particular errors will be shown when accessing Microsoft Direct-X. Gamers will find that some games will crash before the program starts, and others will freeze or crash when a certain point is reached when Direct-X is invoked.
I nearly all cases with this type of error message involving d3dx9_25.dll, the problem is something to do with Microsoft Direct-X. You may also see error messages mentioning similar filenames, as Direct-X utilizes a number of DLL files with similar names.
When you are running a 3d package or a video intensive game, you may see d3dx9_25.dll running in the system processes. The memory usage for this file is likely to be high.