I currently having trouble with several custom maps which I downloaded. The water in these maps looks perfectly fine from above, but when your under-water and look up there is the Missing Texture Purple and Black squares. So you can’t see out of the water.
I currently own Half-Life 2, Episode 1 & 2, Team Fortress 2, Counterstrike Source, Portal, and Day of Defeat: Source. I also have Source mods: Dystopia, PVK 2 and Zombie Panic Source.
I don’t know where I’m missing the textures from.
Here are some of my system specs if it helps. I think I have Direct X 9.0c software, and Direct X 8.1 hardware.
Operating System: 32-Bit Windows Vista Home Premium
Ram: 2 GB (2x 1 GB rams)
Processor: Intel Celeron CPU 2.20 GHz
Virtual Memory: 3.98 GB
BIOS: INSYDE 2.20 9/12/2009