Thanks everyone for your help - I have found the problem. I was
convinced the issue was in the loop and checking of all those rows,
but taking your advice and adding some msgbox prompts at certain
points of the code proved that the loop was fine. It was the code
below which caused the problem. if no data was copied into the
workaid workhseet then the code had most of the empty sheet checked
for the values below.

I've fixed this by adding an if to check if "C4" holds a value and if
not then exit the sub at that point.

Again, thanks for your help.
kindest regards,
Matt



Range("C4").End(xlToRight).End(xlDown).Select
Range("C4", ActiveCell).Select

For Each c In Selection
If c.Value = "PM" Then
c.Interior.ColorIndex = Range("C1").Interior.ColorIndex
ElseIf c.Value = "XD" Then
c.Interior.ColorIndex = Range("G1").Interior.ColorIndex
ElseIf c.Value = "MHE" Then
c.Interior.ColorIndex = Range("L1").Interior.ColorIndex
ElseIf c.Value = "MR" Then
c.Interior.ColorIndex = Range("P1").Interior.ColorIndex
ElseIf c.Value = "" Then
c.Interior.ColorIndex = 2
Else: c.Interior.ColorIndex = Range("T1").Interior.ColorIndex
End If

Next c