Ok, strange one. I produced a document recently which I periodically check on
for accuracy etc. I've opened it up today and for some odd reason the column
labels are no longer 'A' B' 'C' etc but are numbered in the same manner as
the row labels. Also, cell references are changed - for example what would be
cell A1 is now R1C1!?

I'm not sure if this has been changed by someone else or not, but it's
making my monthly upkeep almost impossible! Any thoughts?