Point shapefile freezes mapnik

Dear all,

I've been trying to render a simple point shapefile, however mapnik just locks up (using 100% of one core).
I've tried this both in pure python and using an xml map file (see extract below).

It renders the world_borders shapefile in the Hello World example beautifully, but it won't do a simple point shapefile!

Version: 0.600
OS: Ubuntu Jaunty

Can anyone help please?

Cheers, Will T

<Style name="Style2">
<Rule>
<PointSymbolizer file="/tmp/pub.png" width="16" height="16" type="png" />
</Rule>
</Style>
<Layer name="points" srs="+proj=latlong +datum=WGS84">
    <StyleName>Style2</StyleName>
    <Datasource>
        <Parameter name="type">shape</Parameter>
        <Parameter name="file">pointtest.shp</Parameter>
    </Datasource>
</Layer>