When move_base rotates instead of going straight ahead

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I am facing a peculiar problem with move_base. I am having it read scan input from a hokuyo node laser. When there are no obstacles close by (seen by rviz), I send it a goal of 10m straight ahead, this is within the costmap. In this case, I expect move base to move smoothly ahead; instead, it causes my (physical) robot to rotate continuously in place. I have not enabled rotate recovery. Instead, I find move_base publishes a constant vz velocity.

Can I know the circumstances when this occurs? I can include my yaml files if this is not specific enough.

Update: When I give the robot a goal that requires it to turn (say 90 degrees) and then move ahead, the robot turns, and keeps turning continuously forever without moving ahead. This seems to occur when I make a slight change in params.

Please see my config files here for a config that reproduces this on my robot http://pastebin.com/RriDYkS4