|In the Formula Bar, on the Ribbon, when you select a cell, does it also show #VALUE?|
You could try the CELL() function, try:
=CELL("contents",A1) Displays the actual contents of the cell.
=CELL("type",A1) The type of entry in the cell. Showns b for blank, l for text, v for value.
=CELL("format",A1) If it has a number format, then this will show number format code for the cell.
They might give some clues.