Selecting lines inside a 3d solid

[Anonymous]

When I go to to select or draw a line inside a solid, the face of that solid highlights and will not let me work within it.

[nestly2]

Does it happen in 2DWireframe, or a 3D Visual Style.  Which version of AutoCAD?

Initial thoughts are DynamicUCS, 3DSELECTIONMODE, and SELECTIONPREVIEW