In my current city, commercial buildings are turning into residential buildings without any population. When I buldoze these buildings, they leave unzoned land behind (eventhough it was zoned as commercial before being buldozed). Any idea what the problem is?

I also get this error message when I load my city:
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.
commercial provides jobs but no jobs are set.