I noticed (the hard way) that grenades will slow down and freeze in the air when thrown from the roof of a building on the BluFor side of the MP mission, "Defend Kamino."

They will work just fine if the player is standing (most of the time), but if the player is crouched or prone, the grenades will stop mid-air and stay there until they explode.

I have submitted a screenshot showing what happened with a smoke grenade. It worked with frag grenades as well. {F20359}