1. Yes, DevIL can do mipmapping with OGL. When I said that I didn''t think it could, I was referring only to the ilutGLLoadImage function (which does everything for you).
2. I have narrowed down the error in my code. It occurs in the last line, when I try to delete the image. I tried adding a little error-proofing, but I still get the same same run-time error. (I know it is this line because, when I commented it out, the program ran fine).
Here it is:
if(ilGetData() != NULL) ilDeleteImages(1, &Texs[0]);