I got news!
Ok i did the save, playing from a whdload install on ClassicWB.
I also tested the password check again, and it was successfully passed.
then i moved the sav file outside the emulation and while i was doing it i've noticed that i had also an IsharAGA directory, and that the one i had just played was the OCS version.
So i thought to test and make a sav of that too, and it was a bit of a surprise but the AGA version hangs on saving
(at least in the same area of the map as i saved instead on the OCS version: i haven't tryed somewhere else yet) and also don't pass the password check
Therefore, simply the AGA version of the whdload slave is buggy, it's not a problem of your EXE, but for using it :/
That's unless you have used the Killergorilla pre-installed file for your EXE, as it is mine, and in that case it may be that particular one to have a faulty disk and not eventually the slave to be buggy, but i doubt it.
I also tryed to load the OCS savefile into the AGA one, but i couldn't: i don't know if it is because of the different keymap that the AGA version was using and that complicated the test or because of a different coding of the savegame.
Anyway, for completition' sake, here is the link to the OCS savegame, even if at this point is obsolete...http://ge.tt/8wpEUw4?c
As far as i can tell, both the Ishar AGA slave and your EXE , because of it's use of that, are broken there.
Will you please report it at the Whdload site and or EAB too? I feel I've done too much betatesting for one evening already