I've just upgraded to Ubuntu 13.10 and I'm seeing a strange behaviour. All windows I open have a black, boxy border, including popups, as you can see in the provided image. (The black box in the bottom right is a terminal, which fails to display any text. However, I can enter commands and they execute.) I followed the steps in this post: How do I reset my Unity configuration? to reset Unity using the unity-tweak-tool. Although helpful, that did not fix the issue. I'm thinking this may be a graphics card driver issue.

Any help is much appreciated.