excel 2013 to the rescue…
My wife had a spreadsheet with lots of references and complexity that she was working with for hours. She saved the file in Excel 2007 and something went wrong – she was unable to open or use the file in Excel 2007. She downloaded the original and spent hours working on a second copy. I arrived home to find she was completely frustrated because the same thing happened a second time. We discussed a couple options to try and fix the problem (she had already sent the spreadsheet to someone else to see if it was just her computer/setup/etc.) – finally we opened the file on Windows 8 with Excel 2013:
Excel 2013 not only fixed the issue, it documented the problem (<repairedRecord>Repaired Records: AutoFilter from /xl/worksheets/sheet2.xml part</repairedRecord>) and the saved file worked in Excel 2007 just fine. An enjoyable evening was had by all after solving this problem (I just wish I had arrived before the 2nd round of time filling everything out!)