Weird error when trying to move any object

I’m having a frustrating problem with the GUI.

When trying to move an object -or an edge, face or vertex for that matter- with RMB, grab it with GKEY, or when i LMB click anywhere in the 3D view, the selected object disappears and the header of the 3D view gives me the following message:

dx: -1.#IND dy: -1.#IND dz: -1.#IND (-1.#IND)

I’ve tried to change mode to any of the 5 (Animation, Model…), toggle to Edit Mode, toggle snapping, and change various viewing and editing options around, but with no success.
When I load another old .blend file of mine, things work again. I just can’t use the most recend saved file anymore.

What is that mode I activated without knowing and how do I put things back to normal ?
Thanks in advance !

SHIFT-CKEY fixes the problem.
That’s what I discovered after a lot of trial-and-error.
Considering that, I found the page below. It may explain things, or not. I don’t know much about Blender yet, so it’s Chinese to me.

I hope Google and others index this page, that will probably save a couple days to a bunch of people.