I have two completely different music software programs which can run on my
WinNT4 sp6 machine. Either can process both midi files and their own custom
formats - but not each others custom formats.

So, say
ProgA can handle .mid and .aaa
and
ProgB can handle .mid and .bbb

The problem I have is that when double click a .bbb file in explorer, with the
intention of starting ProgB to load and play the .bbb file, what actually
happens is...
a) ProgA starts up
b) A dialog box pops up (which looks like its from ProgA but *may* be from the
OS/explorer (somehow). The dialog says "cannot open MIDI file". (nb Not .bbb
file). AFAIK the .bbb does not look like a .mid anyway, and I thought the
explorer/OS just looks at the file types!

There is no sign of ProgB starting even thought the file in question IS it's
..bbb file type.

I have tried the "usual" stuff using explorer to associate .bbb with ProgB but
as that process involves SHIFT-RightClick to bring up the "open with" option,
what happens here is that it does a) above, so the assocation may not be being
made.

Is there perhaps a way to explicitly *dissociate* a file type from an
application? If so I could try to dissociate .bbb form ProgA.

Am going around in circles with this one!

tia