Strange change of behaviour, executing daughter programs in Windows

I just tried running a Fortran program compiled (CFV6.6.1) and tested
in september 2004 under Windows.

It calls on about 60 daughter  programs, among them MSDOS editors
(which are called and still work with the associated files passed) and
many for-MSDOS compiled (MSv3.31) F77 programs (which in this mode now
do nothing until ctl-C is struck, when they abort; else just sit there
with a pretty screen and no action in response to other keys.

 All these called programs still work in DOS, and worked when called
under the parent Windows program in 2004 (because of thorough testing)
and probably 2005 or even 2006 because I suspect I used this mode
myself in those years, and because they were "out there" and worked,
without complaints being sent in.

Now I checked on my own Windows NT 2000 Professional and this was the
result.

Anbody got any quick ideas before I start boring you with details?

My own guess is I have to relink the daughter programs with more stack
(I found this to be necessary with even DIRECT execution of some
existing older programs - suddenly.