In the screenshots of shapefiles in this question, Accessing downloaded shapefiles/attribute data?, you can see that the .shp files have the QGIS logo as its icon.
I think this means that on that particular computer, someone tried to open a .shp file directly, Windows asked them what program to use, and they chose QGIS as the default program to open that type of file.
Now, that user is having some unusual difficulties getting shapefiles to properly load into QGIS. Polygon shapefiles are loading into QGIS as point layers with no data in them. I wonder if these problems be related to having QGIS set as the default program to open a .shp file.
I don't want to take the risk of testing this out myself, in case it causes the same problems on my computer. Hopefully someone out there has seen this done before.
So my question is: If you've ever set QGIS as the default program to open a *.SHP file, did it cause any problems?
Eg, shapefile corruption, causing QGIS to misinterpret the data type, etc.