Adding bevels to a simple object messes up the mesh I am modeling a glass top desk, and seem to be stuck at adding a simple bevel to the top of a metal part for the desk. 

In the screenshot below, the first two objects are the same, one in edit mode, and the other in object mode. The mesh on this one is very straight and smooth; it reflects the light like I would expect it to.

As soon as I add a simple bevel to the top edges, it screws up the mesh, as you can see in the third object.

I have tried a bunch of things, including trying to apply an edge loop cut, but have thus far been unsuccessful.

Any ideas?
Thanks to the help from @cgslav, pointing me in the right direction, and from this video: Blender Hard Surface Modeling : Are NGons Bad?, I was able to work out the steps to get the bevels I wanted without the messed up final result. Those steps are as follows:


First, add the bevel to the bottom four edges to convert those
angles to smooth curves.
Now you can add the finishing bevels to the straight edges:
Go into Object mode
Click Smooth in Tool shelf -> Tools -> Edit -> Shading
In Properties Editor -> Data -> Normals, select Auto Smooth
Go into Edit mode
Make sure select mode is set to Edge Select
Press A to deselect all edges
Menu Select -> Sharp edges
Properties -> Transform -> Edges Data
Set Mean Bevel Weight to 1.0
Set Mean Crease to 1.0
Press Ctrl-E, select Edge Data -> Mark Sharp
Press Ctrl-E, select Edge Data -> Mark Seam
Go into Object mode
In Properties Editor -> Modifiers, select Add Modifier -> Bevel
Under Limit Method, choose Weight
Increase number of segments to 4
Set Width to 0.1


Here is the final result:



As you see, the side surface is perfectly flat and straight now. I am very pleased with this, and hope it will help others who come across this same issue.