Exporting and Importing files

[fkimu...@gmail.com]

I have just started using Sketchup and I want to first send a huge THANK YOU to Rob Cameron for his tutorials. I have viewed many tutorials and they either confused me or put me to sleep really fast. Somehow, I just clicked with Rob's tutorials. Perhaps his narrations or voice overs (whatever you want to call it) is like him sitting next to you. All I can say is that it's got me started and I can't get enough. 

Now to my question:

On a separate file, I created a bookcase and wanted to export it into another file. I exported the file as a 3ds. When the import was completed, the subject - lets just say for now its just a rectangle, now has a single dotted angled line attached to each corner whereas the original file had none. Forgive my ignorance but I don't know what they are called - inferences perhaps?. Each part had these dotted lines. I could erase each of the angled lines on each piece but that is taking forever and I don't think that is normal. What am I doing wrong? Am I supposed to prepare the file prior to exporting? Should I group them into one component? Thanks for the assistance.