If you are working with multiple design layers and your "layer options" includes viewing other layers, and ANY ONE of those layers has been switched to a 3d view (like top vs. top plan-as mentioned above), you will get the green tint. You can switch your "layer options" to "active only" and go through each layer to find the one that is contributing the green tint and change its view, or alternatively, change its visibility in the Navigation Palette. I thought I would mention this because if your active layer is in top/plan, and you're still seeing the green tint, this can be confusing.