On Tue, 20 Apr 2010 00:30:17 +0200, Tully Foote <tfoote@willowgarage.com>  
wrote:

> Dan,
> rviz has a feature which will clear all data and buffers if it detects a
> backwards jump in time.  I expect that your playback is looping and that  
> you
> will get this brief error when time jumps backwards.  As far as I know
> that's the only way the grid cell counter would get reset.
>
> The tf error could be caused by a publisher publishing a wrong parent or  
> a
> transform backwards.  But the above sounds more likely from your
> description.
>
> Tully

Thanks Tully, I will look into this!

Dan