Server Physics messed up?

On my server when I put the gamemode on DarkRP (I know, mingbaggery) or Sandbox any CSS weapon that isn’t spawned from the Counter-Strike: Source spawnlist or try to spawn a shipment of anything, it just freezes in midair with me unable to press E on it or move it with the Physgun. Also when any player tries to jump while moving they don’t jump. You can only jump standing COMEPLETELY still. Players also slide around like the ground is ice, but its not like there is no friction. HALP MEH!