I have an Excel File that is haunted by 3 Marcos that I didn't create. It
shows up on the Tools-Macro Lists (alt-F8 on the Excel File), with the Delete
button disabled. When I tried to "Step Into" or "Edit", a messagebox says
the reference is not valid.

I have tried looking for them in the VB Editor (alt-F11 on the Excel File)
with no avail either. I have also noticed in the VB Editor that there is an
extra sheet, Namely Sheet 13 listed on the Tree, which has the same
properties of the "This Workbook" sheet. I cannot delete this sheet 13
either.

These Macros is hording lots of memory and make the Excel file extremely
slow in Response. Please advice.

Thanks in advance.
Aaron