Alright, HL2DM is host to this nasty physics bug where seemingly at random, all object (save players) clipping will start to screw up. Objects won't quite collide with walls as if solid, but will clip halfway through them and bounce back, twirling about as they bounce ghostlike along the floor. After it appears, the bug will persist even after the map switches and won't go away until the server crashes or is reset.
Valve is silent on what causes this and doesn't seem to care to fix it though it's been around over a year now. It shows up mostly in custom maps but steamlab (one of the official maps) has been known to do it from time to time. I've found some luck with reducing the bug by figuring out which maps tend to cause it and reducing the number of physics objects in the map.
Even if I don't play, I try to check the server once or twice a day and reset it if necessary (since leaving the bug on for a while eventually leads to the server locking up to the point where it doesn't crash and I can't even connect). As it stands currently, I think vdeth2 is the map that's been causing problems lately.
So anyway, if you connect to the server and the bug is in play, feel free to pester me to come by and restart the server. Even better, if you connect to the server and everything's fine at first, but during the course of gameplay the bug appears, please tell me in which map it started.
