What I Print Looks Different From What My Screen Shows

I have a WYSIWYG problem: what I see on the screen is NOT what I get out of the print job.

I commonly have the problem when working with Excel objects (any kind of shape, text box, line, graph) in that the layout looks great on the tab that I created, but when I go into PrintPreview or actually print it out, the shapes don't quite align with what I had built in the tab. Where I thought I had lines joining, the print out shows them crossing at other points. If I then go back to the tab and look at the layout on the regular screen, it looks fine.

This problem can be easily understood if you try to create a triangle by drawing three lines (non-overlapping lines that cross only at the vertices). Note that the lines either prematurely cross, or don't intersect at all when you print it out.

THis problem is even magnified when using the camera function to take a "snapshot" of a graph or other objects. In fact, it has the tendency to even "mess up" the graph's formatting, regarding the arrangement of titles and axes (often making them overlap).