Jack,
Try this version:
Sub CreateDesktopFileV2()
Dim WSHShell As Object
Dim DesktopPath As String
Dim FName As String
Dim wb As Workbook
Set WSHShell = CreateObject("WScript.Shell")
DesktopPath = WSHShell.SpecialFolders("Desktop")
FName = ActiveSheet.Range("C6").Value
If FName = "" Then
MsgBox "There is no name for the file in cell C6"
Exit Sub
End If
Application.DisplayAlerts = False
ActiveSheet.Copy
Set wb = ActiveWorkbook
wb.SaveAs Filename:=DesktopPath & "" & FName & ".xlsx", _
FileFormat:=xlOpenXMLWorkbook
wb.Close False
Application.DisplayAlerts = True
Set WSHShell = Nothing
MsgBox "A file has been saved on your desktop."
End Sub