I'm using an Excel 2002 spreadsheet to keep notes. There seems to be
a dead zone at a certain place where I can type in text across about
10 or so columns but when I hit enter everything after the 7th column
vanishes. ...


Excel's built-in Help has a page about "Excel specifications and limits."


For Excel 2003 (what I use), it says:

Length of cell contents (text)
32,767 characters.
Only 1,024 display in a cell; all 32,767 display in the formula bar


Hope that helps.