Thanks Box, you are a genius. Unticking 'use maximum texture size' worked perfectly.
I'll get my Graphics Card updated as well. It's a work computer and tech support is slow.

Hi everyone,

As you can see in the attached images, all my styles have the same linetype.
they are completely broken, and I have no idea what to do. this happens for every single linetype I choose. They all look like marker types.

Please help.