I’m enjoying Black Mesa a lot, it’s top stuff but I encountered a bug a few times where some models are temporary invisible.
It first happened during the cascade sequence: one of the four aliens that approach you disappeared while in full view (no fade or teleport but from one frame to the other he was jut gone…)
Later on the tutorial part where you do your first crouch-jump I got savaged by a invisible headcrab. I heard him, got the damage and everything but he was invisible. He even chased me when I fled into the airduct!
Later it was another headcrab in some corridor, but this time I started flailing around with the crowbar and after I hit I saw it’s body properly.
Another time it was a guard. Very spooky: I heard him talking but he only popped-in when I walked into him.
I run Vista 64 bit, Geforce GTX 560 on DX 10.1 with drivers 301.42
I’m prety far in the game (toxic factory) and all goes well so it’s not breaking anything so far.