I have an autocad 2008 drawing open. When in model space, I am unable to select any of the line that has been placed in the drawing. I can a crossing window over it, tap the mouse button 12 time on a line and nothing. If I let it sit for a while or regen, sometimes that helps. BUt for the most part, the file has become useless do to the inability to modify it. The items that can not be selected are not; an xref, block, nor locked. It was all drawn directly into the file. Not sure if I described my issue clearly. Anyone one to take a stab at an answer?
Try an audit to correct errors in the drawing, save, and then RECOVER to to open the drawing just to make sure there are no drawings errors. That should take care of it.