Issue with copy/paste dates from filtered data

I have a spreadsheet with a lot of account numbers. I have autofiltered to sum a specific account number. I copied and pasted all of the data associated with this account number into another spreadsheet. Everything pasted fine, but the dates changed. For example, the first row of the original data is for 7/1/2004, but changes to 6/30/2000 in the new spreadsheet. Does anyone know why this happens and how to fix so that the dates are consistent between the 2 spreadsheets? Thanks!

One of the sheets seems to be operating with the 1904 date convention -
to rectify this, go to Tools | Options | Calculation tab and uncheck
the 1904 dates option near the bottom. Alternatively, if this is the
one with the correct dates, do the reverse for the other sheet.

Pete

Thanks! That does the trick. What is the 1904 date convention?

Go to Excel Help Index and type "date" - this will explain as clearly
as I can. I think Mac users tend to use the 1904 date system, so you
often get this error in switching files between the two platforms.

Pete