After placing a Tesseract, all TileEntities flicker from green to black and to red occasionally. Other than that, I don't know what else may be causing the issue, but I definitely pinpointed the cause to be Thermal Expansion Tesseracts.

I alter the GLstate a bit, and the thermal smeltery renderer must bork the GLState further...
Not sure... I'm definitely responsible, but I'm not sure If I can fix it at the moment.