i find that it's a lot cleaner create a new material, load that texture and properly map it on the geometry rather than import an image and place it onto geometry from file/import etc.
create a regular material and always check if it's applyed on the front face.. maybe this will help vray to avoid this strange behaviour.. also, if you need to scale/place the texture in a more effective way than the native "texture position" tool, i suggest to give a look at thrupaint by fredo6, thomthom uv toolkit may be helpful too, as it provides a tool to fit texture to quad faces etc..