I have encountered some strange numbering problems on
graphs in a number of my files.  The x axis time values:

1 2 3 4 5 6 7 8 9 10 11 12 13 are appearing in some graphs
as
1 2 3 4 5 6 7 8 9 1 1 1 1

All the graphs's axes label source is the same set of
cells.  Changing the cells to different ones makes no
difference, the difference seems to be in each graph's
settings.  In some other graphs I am getting a similar
problem, the numbers 1-31 having the 20s appear as 2s.  

Interestingly if the axes is formatted as a number to 2
decimal places (in the faulty graphs) you end up
with ...7.00, 8.00, 9.00, 10.0, 11.0, 12.0.

Any ideas?

TIA, Rob