I drew a closed polyline rectangle and SavedAs r1.dxf I then modified the rectangle to add round corners using the 'Modify/Round' tool. It created rounding on all the corners apparently ok so I saved this as r2.dxf
When I then reloaded r2.dxf a large arc appeared on the bottom edge.
I have attached both dxf files and a word doc with a screen shot of what I get when I load r2.dxf (just in case you don't get what I get)
I am using v2.0.2 on WinXP
I have only attached r2.dxf as I can't see how to attach more than one file. If you need the others please ask.