DirectX set to v9.0+ but still getting black/pink checkerboard

I’ve read several posts about this problem. I followed the instructions in Q6 of the FAQ to set DirectX to 9. I opened my Steam library and adding -dxlevel 95 to the launch properties of Black Mesa (I also tried 90, but that made things worse). After confirming DirectX was set to 9, I removed the -dxlevel 95 switch. The problem persists, though. When Gordon goes under water the whole screen is one big black/pink checkerboard. I’ve also set all the textures to the lowest levels possible.

Is there any other solution to this problem?

Thanks.

PS. My computer is really old, but everything else in the game runs fine so far.

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.