Is this script running from the area's OnEnter event? If so, you should delay firing the script until the PC has actually entered the area (and is not still transitioning to it) through something like this:
#include "in_g_cutscene"
void ScriptDelay(object oPC)
{
GestaltStartCutscene(oPC,"summon_pc");
if (!GetIsPC(oPC)) return;
int DoOnce = GetLocalInt(OBJECT_SELF, GetTag(OBJECT_SELF));
if (DoOnce==TRUE) return;
ApplyEffectToObject(DURATION_TYPE_TEMPORARY, EffectVisualEffect(VFX_DUR_CUTSCENE_INVISIBILITY), oPC, 3.0);
SetLocalInt(OBJECT_SELF, GetTag(OBJECT_SELF), TRUE);
object oCaster;
oCaster = GetObjectByTag("NW_ANTIOUS");
object oTarget;
oTarget = GetObjectByTag("SUMMON_PC");
AssignCommand(oCaster, ActionCastFakeSpellAtLocation(SPELL_RESURRECTION, GetLocation(oTarget), PROJECTILE_PATH_TYPE_DEFAULT));
GestaltStopCutscene(2.0,oPC);
}
void main()
{
object oPC = GetEnteringObject();
object oArea = GetArea(oPC);
if(oArea == OBJECT_INVALID) {
DelayCommand(0.5, ScriptDelay(oPC));
return;
}
}
Also, I'm not sure what the GestaltStartCutscene function is doing. So if you're still having problems comment that out when testing to see if that is causing problems.