I’m sorry, but unfortunately your computer does not have the processing power to be able to adequately handle an 8192x8192 texture in the editor, especially Kite Demo assets. Landscapes also take a lot of GPU because the wireframes end up handling significantly more polys than many assets.
According to the error you have given me along with the type of work you are trying to accomplish when this occurs, I can confirm with certainty that this is a hardware issue. Specifically you will need to update these three pieces of your computer:
Processor: AMD Phenom™ 9550 Quad-Core Processor (4 CPUs), ~2.2GHz
Memory: 4096MB RAM
Video Card name: AMD Radeon R7 200 Series
You already mentioned updating the memory, however the other two parts will have to be updated as well to get reasonable results, especially with any rendering activity that you attempt to do. I would recommend a minimum of these replacement parts, especially if you are trying to render any kite demo assets:
CPU: 4 cores (minimum i5) @ 2.8GHz
GPU: Nvidia GTX 680
Until this is updated, there is nothing I’m going to be able to do to further assist with rendering freezes because they are hardware dependent.