This week's tip starts with a riddle.

What layer can be created, that when on, thawed, and unlocked, will not allow objects to be selected with the cursor unless the 0 (zero) layer is on and thawed also?

Defpoints.  Yes, that's right folks.  Draw some entities on the defpoints layer, turn off or freeze layer 0 (zero) and then try to select the objects on the Defpoints layer with the cursor.  Single pick, crossing right to left, left to right, anyway you try to select the objects it can't be done. 

Solutions for Autodesk Map 3D 2006:

• Simply make layer zero on and thawed to fix the selection problem. 
• Use the previous option at any select object prompt, regardless of the layer state of zero.
• Freeze all other layers except Defpoints and use the all option at a select objects prompt.