kinect: nonsense point clouds for 30 seconds after subscribing

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I launch the kinect driver and processing nodes with openni_launch/launch/openni.launch. I have the latest versions of the ROS-openni packages in Electric. I get xyzrgb point clouds, but the depth data is nonsense for 30 seconds after subscribing. Here's a video, where I'm viewing the point cloud in rviz on a remote computer: http://surgical1.cs.berkeley.edu/troubleshooting/rviz_kinect.ogv. This isn't a network issue--I have the exact same problem when I record data on the local computer that the kinect is connected to--c1 on the pr2.