i've had similar problems and i solved it by selecting the row following the
data and then selecting all rows  until the end... delete  them using the edit
menu.. then save it.. then I check for last row by using control + end.

i've only had this fail me once, and that ended up being a file that once
had a virus that was cleaned but something was still messed up so I just
created new workbook and copied data over to the new book.