Graphics disappearing in beta4

[registeringislame]

I'm running on linux, and when I change the tileset twice or so, all my graphics turn into white blocks. Some are different shades (so lighting still seems to work) and sometimes the player character symbol remains, but everything else goes. Even when I change tilesets the graphics stay the same. (Some characters change, if there are any left. So if I can still see doors for instance, they'll change).

I also have unrelated problems with the text in shops. If the list of items is too long it will overwrite the price information.