The glass shader issue *only* occurs with the new Path Tracer rendering system, which is still in development and *not* recommended for regular use. If you use the old, normal rendering method, the glass shader renders the same as it used to. So no need to uninstall for that.
Also Terragen doesn't use the graphics card for any part of the rendering process, so testing the path tracer or other high settings is not really going to help you determine if a new graphics card is needed. I'm not sure if that was what you meant when you mentioned that though.
Ulco, I didn't mean you, the path tracing builds are public now so a lot more people have access. I'm just surprised more people aren't testing it out, but probably most aren't aware it's there as we have (intentionally) not made a big fanfare of it yet.
- Oshyan