Hi,
The "strange" symbols and gray boxes you see in your drawing are Parametric Constraint Bars:
They are the result of applying Parametric constrains to the objects in your drawing:
If you are not sure about Parametric Constraints and do not need them in your drawing, I'd suggest you at first to delete them all: use menu Parametric->Delete Constraints and when AutoCAD will ask you to select objects, type ALL from the keyboard and hit Return:
Command: _DelConstraint All constraints will be removed from selected objects… Select objects: ALL 2 found Select objects: 1 constraint(s) removed Command:
This should delete all constraints in your drawing.
If you are not aware about Parametric Constraints, and don't need them - don't use them in future.
Avoid to use Parametric tools from Draw tab of Tool Sets palette:
And keep Infer Constraints OFF on the Status Bar:
And of course, you need to follow John Vellek's suggestions about Z values of the objects in your drawing.
You can also attach your drawing here - I'll look at it.
Maxim