A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Hi Guys, I just found this information on some other blog:
"It’s not necessarily “External data”; it's actually the Pivot Cache that it wants to clear, so the message is legitimate, but, in true Microsoft fashion, it's not really clear. If you click Yes to the message, your workbook size on disk will be smaller because the cache(s) are thrown out, but it will take longer to open the WB because Excel will rebuild each and every one as it opens, then refresh all the pivots."
It doesn't resolve the annoyance, but it puts my mind at ease that nothing is lost whether you click Yes or No.