Unusual non-removable object on sheet

[GregOb]

Ran into this previously and resolved it but cannot remember how or find anything out there on it. On one sheet I have a small white box I can't get rid of, even deleting the row or column just moves it slightly. This tell me it's somehow tied to the sheet, not the cell. When I zoom in as much as possible and click in the upper left hand corner it provides a small drop-down with years in it. The cell and surrounding cells have some conditional formatting applied, but only to change background color depending on the value. Can anyone shed light on where this comes from and how to eliminate it and keep it from recurring?

Thanks,

Greg