Hi Greg, one other thing that I should mention is that if you use "Open" the viewports will automatically zoom to fit the objects that were loaded.

If you use "Import" (where it merges the objects with the current scene), it does not alter your viewports.

So it is possible after Import that you can have things that you just can't see at the current zoom level. After you do an Import you can push the "Reset" button inside of a viewport though (right click to apply to all viewports) to zoom out to see all current objects.

- Michael