Hi Ian,

>1) Why ShellExecute is not using the Default Verb , or

That would happen if there's no default action associated with the file extension. In this case, ShellExecute() uses the first verb which might be "print". It could be that Explorer isn't using the first one, rather tries open and edit before resorting to something else.

File associations are stored in HKEY_CURRENT_USER\Software\Classes.