Slow observation buffer update warnings in move_base

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Hello,

I'm using a sick laser (lms-200) and a kinect camera as my sensors, mounted on a pioneer 3-at. I'm running ros diamondback on ubuntu 10.10, running gmapping with the nav stack.

I know from rostopic that the laser is publishing scans at around 10hz, however, I keep getting such warnings from move_base.

[ WARN] [1317944137.717114373]: The /scan observation buffer has not been updated for 5.18 seconds, and it should be updated every 5.00 seconds.

[ WARN] [1317944137.917127486]: The /scan observation buffer has not been updated for 5.38 seconds, and it should be updated every 5.00 seconds.

[ WARN] [1317944138.117128035]: The /scan observation buffer has not been updated for 5.58 seconds, and it should be updated every 5.00 seconds.

[ WARN] [1317944138.317100694]: The /scan observation buffer has not been updated for 5.78 seconds, and it should be updated every 5.00 seconds.

[ WARN] [1317944138.581264407]: Map update loop missed its desired rate of 1.0000Hz... the loop actually took 4.9738 seconds

Why does it take so long for the scan msg to register with move_base? Is it related to the slow map update warning at the bottom? The result is that it takes minutes to plan any simple path. Any help would be greatly appreciated! Thanks!