Luc,

> The main datamodul is the first unit created in the project
> and it's (old habit) always the first opened unit in the IDE.

But is its design window open, or only the unit source? Make sure you
open the design window for the main datamodule and see what happens.
I dont mean to harp on this, but I know that it makes a difference in
the problems that I have seen.

> Any more ideas?

Not many, designtime problems are always a pain. Is there anyway you
setup to try cause the problem at runtime? Perhaps setting up your
main form so that it does not create anything else but the main and
problem datamodules and then trying to prepare the query. If you can
cause the problem at runtime we can get a callstack and get some idea
where the problem is originating.


Geoff Worboys
Telesis Computing