Steps to reproduce:
- In Rhino, create a plane surface.
- Assign a new material, type Custom.
- In Material Properties > Textures > Transparency, load some image (I tested PNG, TGA - both crash).
- Start Enscape. The surface is displayed correctly, with transparency.
- In the properties of the transparency map > Output Adjustment, change anything. Click OK.
- Enscape crashes with a fast exit, including Rhino.
Thanks for looking into this!