Tipster Daniel Jurado created a macro to tidy up AutoCAD Civil 3D and AutoCAD Map files, but his tip should work in all versions of AutoCAD.
"This is a macro I made for one of my tool palettes. I believe it will work with all versions of AutoCAD, as it uses commands straight out of the box. The macro thaws all layers, turns on all layers, sets the current layer to zero, unlocks all layers, zooms extents (to force a regen), then zooms previous to leave you in the same spot as before."
Notes from Cadalyst Tip Patrol: This macro will ensure everything is turned on, visible, and refreshed. The zoom extents then zoom previous simply zooms out, then back again. This forces AutoCAD to perform a screen regen, smoothing all of your linework. This would be a good macro to run before you save and close a file, or when you open a file from a third party.