Material removal

Unity Engine
1

There is a strange thing going on in my latest project!
When i get the color variable of meshrenderer.material.color and do not even assign it to anything, the material of the prefab from which i instantiated the object gets removed AFTER stopping the game in test mode. Now the strangest thing of all is that i use the same meshrenderer.material.color on another gameobject and this gives no problem at all. I’m truly clueless, any help is appreciated.

[EDIT]
a Video of the problem: http://www.youtube.com/watch?v=KXlh2FbGu4s
[/EDIT]

Some snippets from my code:

    //////////////////////////////////////
    // WoordenGM.cs
    // if this meshrenderer.material.color is called, after the scene is closed the material is removed from the symbol prefab!! 
    // (see bug ->)
    //////////////////////////////////////
     
    public GUIStyle symbolButtonStyle, symbolLabelStyle;
     
    void OnGUI()
        {
            if (gameManager.play  !gameManager.win)
            {
                if (showSymbolString) { DrawSymbolString(); }
                gameManager.menu.DrawMainBackground(buttonMenuHeight);
                drawSymbols(buttonMenuHeight);
     
                gameManager.menu.DrawTopbar(gameManager.menu.selectedGame.Name, 120, true);
                gameManager.menu.DrawStatusBar(gameManager.menu.selectedGame.Name);
            }
            else if (gameManager.play  gameManager.win)
            {
                drawWinScreen();
            }
     
        }
     
        /// <summary>
        /// Draw the name of the dragging symbol
        /// </summary>
        public void DrawSymbolString()
        {
            GUIContent content = new GUIContent(activeSymbol.name);
            Rect rect = new Rect(Screen.width / 2 - 200, 200, 400, 60);
     
            // bug -> removes materials from prefab when assigning the matrial color to textcolor
            symbolLabelStyle.normal.textColor = activeSymbol.GetComponent<MeshRenderer>().material.color;
     
            GUI.Label(rect, content, symbolLabelStyle);
            //symbolLabelStyle.normal.textColor = Color.black;
        }
     
    //////////////////////////////////////
    // Symbool.cs
    // If only this meshrenderer.material.color exists, the material wil not be removed after playing scene
    //////////////////////////////////////
     
    public void Destroy()
        {
            if (explode != null)
            {
                ((ParticleSystem)Instantiate(explode, transform.position, transform.rotation)).startColor = ((MeshRenderer)transform.GetComponent<MeshRenderer>()).material.color;
                Destroy(gameObject);
            }
            else
            {
                Destroy(gameObject);
            }
            if (woord != null)
            {
                woord.symbool = null;
            }
        }
2

SOLLUTION:

I don’t know why, but using .sharedMaterial instead of .material did the trick.
My quess is that the gc cleans the cloned object and sees the original object as the same.