Followed your advice, which totally makes sense. However, the same problem still happens. I even tried using the SetActiveChildren, Self and just SetActive.
When a character collides with a cube, I want to pop up the progress bar and have it at 0.0. When the character presses "y". the slider should go from 0.0 - 1.0. If the character stops colliding, the slider should fall back to 0.0 and disappear. If the user lets go of Y before the slider hits 1.0, I want to reset it to 0.0 and then disappear. If the slider hit's 1.0. I want to reset it to 0.0 and make it disappear.
Stack trace below.
Destroying GameObjects immediately is not permitted during physics trigger/contact, animation event callbacks or OnValidate. You must use Destroy instead.
UnityEngine.Object:DestroyImmediate(Object)
NGUITools:DestroyImmediate(Object) (at Assets/Plugins/NGUI/Internal/NGUITools.cs:514)
UIPanel:OnDisable() (at Assets/Plugins/NGUI/UI/UIPanel.cs:705)
UnityEngine.GameObject:SetActive(Boolean)
NGUITools:SetActiveSelf(GameObject, Boolean) (at Assets/Plugins/NGUI/Internal/NGUITools.cs:669)
AmountStolen:OnTriggerStay(Collider) (at Assets/Scripts/InGameHUD/Amount.js:53)