Hi All,

I have done a bit of background and can't find an answer for this particular problem I am having.
I am currently running Excel 2007.
I created a spreadsheet in 2007 with data validation referring to 'lists' on a hidden tab in the same workbook.
I have sent this to 10 colleagues. the colleagues with Excel 07 can see, edit and save without a problem.
One colleague has Excel 2010 (though it will soon be rolled out to all staff in the company)
I have already had to change all the referencing for the list to '$' absolute referencing as Excel 2010 was reading it as dynamic. That problem is now solved.
However, I am finding that everytime I receive the spreadsheet back from the user with 2010. When I open this workbook on my 2007 system - I no longer have the dropdown lists or data validation in the cells it did apply to.
I look at the same book he sent me (using his laptop) and I can see the lists. Yet somehow once it comes back to me the validation rules/lists are gone.
Please note the "hidden" second tab is still there and hidden in the workbook he sends me. He says all he is doing is opening, selecting answers, saving and emailing - without changing any formatting or anything.

Has anybody got any ideas with this?? The IT dept here aren't exactly pro-active at these sorts of problems.

Any help would be greatly appreciated