I was trying to correct the country shapefile of Uzbekistan for Gas flares:
In QGIS the result was that the overlapping regions - where the differencing should have taken place - were gone. I presumed it was due to wrong referencing of the UZB shapefile. Couldn't resolve it somehow. After several desperate hours I went to gvSIG 2.2, did the differencing job there. And it worked like a charme. Has anyone an Idea what was wrong in QGIS?