Ha. You may have an interesting problem here. Seeing that you have access to GDAL, and assuming you have access then to ogrinfo.. please adjust this expression and run it against your dataset to check for the distinct geometry types it contains:
Use OGRINFO to Return the Distinct Geometries in a Dataset
ogrinfo "D:\LongPathTo\Data\MyPolygons.shp" -geom=no -sql " SELECT DISTINCT OGR_GEOMETRY from MyPolygons "
Basically what I'm doing here is asking ogrinfo, by way of OGR SQL to show me a list of the distinct geometry types it encounters in my dataset. For my example, the output is like this:
C:\Documents and Settings\soloorbit>ogrinfo "D:\LongPathTo\Data\MyPolygons.shp" -geom=no -sql " SELECT DISTINCT
OGR_GEOMETRY from MyPolygons "
INFO: Open of `D:\LongPathTo\Data\MyPolygons.shp'
using driver `ESRI Shapefile' successful.
Layer name: MyPolygons
Feature Count: 2
Layer SRS WKT:
OGR_GEOMETRY: String (0.0)
OGR_GEOMETRY (String) = POLYGON
OGR_GEOMETRY (String) = MULTIPOLYGON
So in this case---note that I have both POLYGON and MULTIPOLYGON types in this dataset. That's because ESRI allows that by default. But often, the open source stuff is more restrictive, and you generally have to say "hey this is okay!", or alternatively explode your multipart polys into single part.
....but more than anything, right now I'm just curious how many distinct geometries you have in that table. I wonder if it could be a null geometry?
CAVEAT: I've noticed the double-quote symbol (") has a tendency to get strange once it's posted into a web thread, so I highly-recommend just typing out the full expression into either notepad or your command window first, rather than merely copy/pasting it, then tweaking it.
Best / Elijah