Used COUNTIF to count the # of occurrences of various letters in a table with
one letter per cell. Double (+) checked all formulas, ranges and results.
Each letter was counted correctly except the letter 'i' whenever it appeared
in a subset of cells within the table. Double (+) checked that I was
actually using the letter 'i' and not lowercase 'L' or anything else that
looked like 'i'. Substituted other letters in at least some of the subset of
anomalous cells and all worked ok. Also, substituted other letters in the
COUNTIF formula initially being used to count 'i' and all worked ok. Played
with the insertion of 'i' in various portions of the subset of anomalous
cells and in various insertion orders, and the problem persisted UNTIL I
inserted 'i' in one particular cell. Now that I've done that, all appears to
have corrected itself.

Any ideas regarding what may have happened?