You can save an Excel document in Excel and immediately re-open it and have Excel complain the document is corrupted. It's happened to me dozens of times (back

You can save an Excel document in Excel and immediately re-open it and have Excel complain the document is corrupted. It's happened to me dozens of times (back when I was required to do Excel development a couple years ago... it was like a flashback to 1990). Anyhow, every time it happened, there was no apparent damage to the document. I think this stems from Microsoft having to be insanely aggressive in defending against their own bugs.