Any time you have a volatile function (e.g., NOW(), RAND(), TODAY(),
INDIRECT(),OFFSET(),ROWS(),COLUMNS(),CELL()), and the sheet is
calculated when opened, it will mark the file as being changed and
needing to be saved.

In article .com,
wrote:

This is kinda annyoying. I opened the excel file and didn't do anything
and immediately closed it. However, Excel asked me if I want to save
the changes?
Anybody knows why this could happen. There is no macro in the file,
although it has a few combo boxes. Could that be a problem?
Thanks in advance