bouncy physics bug

[Drewbert]

Has everyone else seen this bug? it's where all the physics objects start lying halfway through the floor, and hanging from the celing, and bouncing around like weightless balls.
What causes this and is there something in my map that could be triggering it?

 

[Ennui]

Its a problem with Source. SourceForts had a massive problem with it.

 

[Fender357]

Its a problem with Source. SourceForts had a massive problem with it.

One of those new HL2DM maps has a big big problem with that too. Not to mention their weapon placement sucked.