I am having an issue whereby when I close an re-open my file drop down lists are disappearing - in the sense that the cell data validation reverts to being set as 'Any Value'

I have scouted google and can only find solutions that suggest:

1. make the file and xlsm- which mine already is
2. make all lists draw from named ranges - which mine now are after trying this

It also suggests this is mostly an excel 2007 error - but I am on 2010.

I have tried deleting the cells and re-setting up the lists. I am really trying to avoid having to re set up the workbook - that really is not a viable option unless I have no choice at all.

Apologies if this has been answered before but I have been googling to no avail beyond those solutions I have given.

The error message states: "Excel was able to open the file by repairing or removing unreadable content"

Any suggestions?