Not a bug, I have the same issue on my laptop.
The reason has something I believe with the graphics card on the computer, and unfortunately in my case, I canno upgrade the card as it is integrated in with my system.
If you look in the EC forum, I believe you'll find the requirements for the system to run the EC w/o issue, and this is how I discovered my laptop was not up to the task.
Mind you, my computer is probably 5 years old, so, meh, wasn't a huge deal for me.
I do however recomend give Pinco's UI a try, as he has put a lot of work into it, where you can work around the missing artwork in your pack.
However, some of the artwork will just be missing, and this is something I have learned to adapt to, as I genuinly do love playing UO on the EC.
Hope that helps!
