Hi,
I am a fairly experienced user of XL but I still have not found an
explanation for this happening...

Sometimes a workbook will suddenly switch to a page PER CELL for every
worksheet within it (and all other open workbooks as far as I can tell).

Has anyone seen this before and know why it happens? Once it happens i can't
find anyway of reverting to normal except by closing and not saving (I've
tried all the obvious page setup options etc.)
Thanks in advance.