Problems with HL1 Textures

So in celebration of the Black Mesa release announcement, I decide to go and make a pose on one of the Black Mesa (not from the mod) maps.

However, I’m encountering a problem, as you can guess.

Various textures for what looks like mainly elements of the map that are supposed to show a light are broken, with this weird stained glass-ish overlay appearing on them. It seems to be a recent thing, because I’ve used these maps countless times before without any problems.

Any guesses at what I can do?

May be a graphics card problem, or you installed something that fucked them up.

Have you tried just taking the materials from the Half Life gcf?
Just try opening it up and pasting them in your half life folder, in their respective folder locations of course.