--- Operating System, Graphics card ---
Ubuntu 12.10, Beavercreek

--- Blender version with error, and version that worked ---
2.67b

--- Short description of error ---
If an object uses the shrinkwrap modifier, and it's scale is set to zero, then it freezes Blender, and I have to restart the computer.

--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
1> create 2 objects,
2> shrinkwrap one to the other.
3> select the one with the shrinkwrap modifier
4> press s to scale and type 0.

The entire computer completely freezes up!

I often skale objects to zero to make them disappear.