I had several macros that have worked for months with the VLOOKUP Function. I went into my office to run my morning report macros and they started failing with the RUNTIME ERROR 1004 Application-defined or Object-Defined error where the same macros worked the day before. I found that in the target lookup table reference, the macros that specified RC endpoints worked but the ones that specified whole columns didn't. Is there an option or feature in Excel 2007 that could have been toggled or changed that would allow one to work and another to not work? Nothing in the macros themselves changed.