I've been successfully using Access 2007 to import sheets from Excel 2007 for
several months. Last week, without any changes to my computer (that I'm
aware of, other than MS automatice updates), when importing I get a message
that the Excel file is in an Office 2007 beta format and cannot be used. I
never had Office 2007 beta on my machine. After a systematic set of
diagnostics, I found that if I save the Excel workbook in .xlsx rather than
..xlsb (which I had used without issue for months), the issue does not
reappear. While this workaround does not impact me, I wonder if anyone else
has seen this behavior. I duplicated the issue on a brand new laptop with
very little activity (again, other than MS automatic updates). This is in an
important production program and it makes me nervous when these type of
anomalies pop-up without apparent basis. My suspicion is that a MS update
broke something, but have no proof.

J Austin