how do I open a DXF file to a 2d sketch without the errors

I am trying to open my 2d sketches from Sigmanest 8.1 . I export them as a dxf file and when I use the solidworks wizard to open them it sometimes works and other times I get an error saying it's 228 points are out of modeling limit and 13 entities could not be imported. Then if I take a sketch in solidworks premium 2011 and save it as a dxf file and then try to open it with the wizard it does the same thing so it must be a glitch in solidworks. Is there any way around this? Also I can import it as a 3d model but then I cant extrude it or do anything with it. Any help would be great

SolidworksSketching