Incorrect column widths in IE8, Chrome22, FF11.

Test code:
<grid width="971px">
<auxhead>
<auxheader width="571px" label="Column 1" rowspan="2"/>
<auxheader width="70px" label="Column 2" rowspan="2"/>
<auxheader label="Column 3" colspan="3"/>
<auxheader label="Column 4" colspan="3"/>
</auxhead>
<columns>
<column width="70px" label="Column 5"/>
<column width="70px" label="Column 6"/>
<column width="70px" label="Column 7"/>
<column width="70px" label="Column 8"/>
<column width="70px" label="Column 9"/>
<column width="70px" label="Column 10"/>
</columns>
<rows>
<row>
<label value="String 1"/>
<label/>
<label/>
<label/>
<label/>
<label/>
<label/>
<label/>
</row>
<row>
<label value="String 2"/>
<label/>
<label/>
<label/>
<label/>
<label/>
<label/>
<label/>
</row>
</rows>
</grid>