I know I had this problem before and somehow fixed it, but when I am rendering, all my glass surfaces are rendering black. Help.
I don't know.
Can you post a stripped down model that we can try?
Make sure that the glass is not black in SketchUp. SketchUp lets light pass through black glass which is transparent.
IRender nXt defines "black" as "allows no light to pass through it" - even if transparent. So you may need to make it dark grey instead of black.
We try to compensate for this, but sometimes it fails.
As Rich said, send us a small model (e.g. one transparent surface with black glass) and we will take a look.