I'm puzzled by your comment about macros.
Simply, the R1C1 style referencing in EXCEL became switched on for some reason.
You can turn this on/off using the options in EXCEL. Each EXCEL version puts this somewhere different in the menus, but for EXCEL 2007 for example you do the following:
Excel Options
Formulas - make sure that there is no tick in the box called:-
R1C1 reference style