[Celjabba]

SOLVED ! Victory.

All hail the mighty google :)

So....

When you set a DEP exception, you actually create a registry entry in

hkey_local_machine\software\microsoft\windowsNT\cu rrentversion\appcompatflags\layers

wich have the .exe path as name and DisableNXShowUI as value.

BUT

If you crashed the application before that, windows in some case create a key with value disableusercallbackexception. Same name, same emplacement.
(apparently, this is a windows attempt to prevent further crash. or it may be linked to compatibility mode. not sure.)
If that key exist, the DEP exception cannot be written, and does not work.
(but appear as valid in the exception list)
Deleting the disableusercallbackexception registry entry and then setting the DEP exception work.

Perhaps this may help someone else ?
If not, any moderator may delete this thread :)

Celjabba