When TR_m4_Duvlas force greets you after asking around for a while all is fine. However if you kill her in one shot the script goes into a state that causes every dialogue related action to hang. This gets saved in so after saving the savefile is corrupt too. This goes all fine if she does not die at once.

just a wild guess but:

if ( doOnce == 1 )
    if ( GetHealthGetRatio < 0.25 )
        SetFatigue 100
        ForceGreeting <= NPC is allready dead?
        return
    endif
endif