I see shadow already fixed it. but just encase you wanted to know what was happening. I placed comments on each one of your brackets at the bottom of you script for what they started and what they where the closing bracket for. If you note the function you where useing to advance oTarget was outside of the while loop. therefore the loop never ended.
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while(GetIsObjectValid(oTarget))
{//Start While
RemoveEffectsFromSpell(oTarget,GetSpellId());
.
// * GZ Oct 2003: If we are silenced, we can not benefit from bard song
if (!GetHasEffect(EFFECT_TYPE_SILENCE,oTarget) && !GetHasEffect(EFFECT_TYPE_DEAF,oTarget))
{ //Start If level 1
if(oTarget == OBJECT_SELF)
{ //Start If level 2
effect eLinkBard = EffectLinkEffects(eLink, eVis);
eLinkBard = ExtraordinaryEffect(eLinkBard);
ApplyEffectToObject(DURATION_TYPE_TEMPORARY, eLinkBard, oTarget, RoundsToSeconds(nDuration));
if (nHP > 0)
{//Start If level 3
ApplyEffectToObject(DURATION_TYPE_TEMPORARY, eHP, oTarget, RoundsToSeconds(nDuration));
}// end if level3
}//End if level 2
else if(GetIsFriend(oTarget))
{ //Start If level 2
ApplyEffectToObject(DURATION_TYPE_INSTANT, eImpact, oTarget);
ApplyEffectToObject(DURATION_TYPE_TEMPORARY, eLink, oTarget, RoundsToSeconds(nDuration));
if (nHP > 0)
{//Start If level 3
ApplyEffectToObject(DURATION_TYPE_TEMPORARY, eHP, oTarget, RoundsToSeconds(nDuration));
}// End if level 3
}// End if level 2
}// end if level 1
}// End while loop.
oTarget = GetNextObjectInShape(SHAPE_SPHERE, RADIUS_SIZE_COLOSSAL, GetLocation(OBJECT_SELF));
}//End Main.
