Get us a few examples of the file names in the folder as well as a few examples of what you have in Column C

Everything works like a dandy here.

For i = 17 To Cells(Rows.Count, 17).End(xlUp).Row
Should that not be
For i = 17 To Cells(Rows.Count, 3).End(xlUp).Row
If your comments and names are in Column C

Otherwise attach your workbook without sensitive data.