Automation Error - Catastrophic Failure EXCEL VBA

Question

I have a workbook which is throwing this error on opening. When it does and I open the VBA module, the current line is the definition of a sub. But the only option is to kil

Answer 1

Double-check your file extension. Excel spreadsheets with macros embedded need a *.xlsm extension, not *.xls.

Total 'for-dummies' answer, but I just made this mistake myself.