I often open a .csv in Excel for Mac, then do things like Pivot tables which add tabs. Then I go to save, and I guess the default setting is ".csv" - i.e. the file type that I began with, and if I am not EXTREMELY careful and change the file extension i LOSE ALL MY WORK - i.e. everything but the sheet which was in view when i closed the document. No warnings, no nothing. This is one of the rare times I would actually appreciate a warning that I am about to lose the last 4 hours of my life. I have changed the default file type in "Compatibility" to "Excel 2004 Workbook", but this does not seem to help. Is there perhaps a flag somewhere in which Excel will be intelligent enough to know that when I add another sheet in a workbook, I am in danger of losing my work since the original file type was ".csv"? I never had this problem with XP/Excel. Back in Bill land turning a CSV into a workbook changed the file type automatically. Is this some type of evil trick by Bill, or for the conspiracy minded - Steve? Any tips for this?