I am trying to merge several excel workbooks but before running my code
I want to check if all required workbooks exist in a directory.

The master document consists of 3 sheets. Each sheet has employee names
in the first row, starting at column D. The number of employees can
vary (the last employee will be the one just before the column with the
name "TOTAL". Each name followed by .xls is a workbook that should be
present in the directory.

The code checks if these files exist in the directory. If they all
exist and there are no other files present, the code will execute; if
they are not all present or other files exist, code should stop
running, displaying a message that xxxx is missing or an unknown xxxx
files has been found in the directory.

Thanks in advance.

Mark