I recently started using draftsight as an alternative to the aging CAD package on my computer.  Ive been using it for a couple of weeks on my laptop with no issues, but I installed it onto my windows 7 64 bit desktop machine today, and when I open a .dwg file, I can see the preview, but then the file does not display in the model space.  The name of the file isopen for editing but I cannot see the drawing.  .Any suggestions?