Hi Brian,
I hope all is well, thank you for getting back to me. Yes, that is what I was seeing/reading, the odd thing was I wasn't getting any render using the "render to disk" - or at least I thought I wasn't!
I could see it was generating an image file, but then it was stating that the file was broken....
Then, just tried it again and realised it was a complete noob mistake!! So the issue was, I was setting the filename to .png as a quick test, but I left the file type to exr, so the image format was broken - DOH!!! So I now have made sure the below items match up!
Now I just need to work out how to render the Arnold USD files, the .ass files render but not .usd - next hurdle

Also need to figure out shaders, as everything is grey at the moment, except when I loaded the .ass export from Maya - lots to do!
Actually, I have got usd working, it just didn't have a shader attached, just need to figure out shaders with usd within houdini, I created an arnold surface shader and assinged it to the usd and it showed up etc!
OK last bit of waffle from me! It turns out that the USD file I was loading didn't have textures working, or they were broken etc, I loaded in two other usd assets and they are fine and load!
I would say this is sorted now!!
Thanks again for the help.
Iskander