As an aside, if you want to render a lens flare on its own layer, here's a little trick:
1: Go to Layer > New > Layer... (don't use the shortcut button on the layer palette, as it doesn't bring up the options dialog)
2: Change the mode to "Overlay"
3: Check "Fill with Overlay-neutral color (50% gray)" and click OK.
You can now render a lens flare on this new layer. It also works with several other filters too, but as pixl8r points out, you must be careful with what color mode you use.