I have a column with dates in it and I am running the following macro:

Sub colr()


Range("e2").Select
Do
If Now - ActiveCell.Value 30 Then
ActiveCell.Interior.ColorIndex = 3
ElseIf ActiveCell.Value Now Then
ActiveCell.Interior.ColorIndex = 34
End If
ActiveCell.Offset(1, 0).Select
If ActiveCell = "" Then
Exit Do
End If
Loop Until ActiveCell.Value = " "
End Sub

Macro runs fine, however it stops when it comes to a blank cell or a cell
with a question mark (?) in it. How can I change this macro to bypass if the
above occurs.

I actually want it to run until it gets to the bottom of the column and hits
a blank cell there and then stops.

Thanks
Frank