I just upgraded to Windows 7 and I'm trying to figure out how the "default programs" works. Basically, can an external program override the program set in the [Set Default Programs] option? For example, I installed a media application (KMPlayer) that does not show up in the [Set Default Programs] list. Now in the KMPlayer's preferences, there's a setting to associate file types with itself. But when I tried that, I noticed that the files still default to Windows Media Player. So can I assume that no external application can change the program associated with a file type unless explicitly done via the: + [Set Default Programs] or + [Associate a file type ... with a program] or the + [Open with...] options? Thanks in advance!

So can I assume that no external application can change the program associated with a file type unless explicitly done via the: + [Set Default Programs] or + [Associate a file type ... with a program] or the + [Open with...] options? Thanks in advance! May be the program is writing only to the per-machine part of the registry. In that case, the per-user settings take precedence. It's possible for a developer to write the file type associations directly to the registry, without using the Set Default Programs or any other GUI. Also note that Microsoft has provided detailed guidelines for developers to register their programs with "Default Programs" Default Programs: Ramesh Srinivasan, Microsoft MVP [Windows Desktop Experience]

Thanks for clearing that up!

YW, kl90.Ramesh Srinivasan, Microsoft MVP [Windows Desktop Experience]