This post is subtitled Undos that Do and Those that Don’t
If you’re using Excel 2003 or earlier, you have a big problem with the Undo command, you see much of the time, it plain doesn’t work.
Curious? Try this: open an Excel file, make some changes to it (minor however, you won’t be able to undo these however much you think you can). Check the Undo button – it is enabled. Save the file. Now check the Undo button again. Yikes, it’s now disabled. You see, after you save a file in Excel 2003, all the Undo steps are removed – no more Undo. It pays to know this is how it works.
In Excel 2007, things are much better, and the Undo retains the changes even after you have saved the file. Much nicer behavior.