[neuralassassin]

Unfortunately I've seen that error with and without nUI installed, as have many others if you do a little search on google you will see plenty of threads on it. Most with no solutions, in my case it seems to have to do with wow loading to many textures at once. It happens usually while flying through northrend, but I have seen it other times too. First thing you should check is that your RAM is running at the correct speed and timings.That has helped some people, might wanna run the memory through memtest86 also to check for errors. Other people reported that turning down your graphics settings a little seems to help, if none of that works you can try posting in the wow tech support forums but because of how common the error is I don't know how much they can help.