Just an update on my issue, maybe this will apply to other Nvidia users. I found a forum elsewhere were a guy solved the opengl crash by *under*clocking his GPU, setting its power and such lower than factory. I've tried this on mine, which I only just noticed is described as "superclocked" and it seems to be working so far with a TG3 render. I've done a total of about 2 hours rendering so far, in crops, before I was getting crashes inside 45 minutes (fingers crossed). Apparently some high-end video cards come with factory settings close to their limits. However, If this ends up working for good, it will leave me wondering why TG3 crashed, but Rift (an MMORPG) on max settings did not, seeing as Terragen 3 doesn't seem to make much use of the GPU.