Can`t open file

Hi, I'm Peterson.

I'm Brazilian using Ubunto, and I've just downloaded the latest version for my system at 3ds.com.

My question is, why can't open files?

I've just created a design and after saving, I tried to open it and i couldn 't. The DraftSight says my file doesn't exist... It happens when I try to open any other file to....

That's frutrating because I spent a few hours at night making this work, and was so excited with this CAD. Please HELP!