Welcome to the board....
It's like a circular reference...
You're using the Worksheet_Change Event to make a CHANGE to the sheet, therefor triggering the change event again, over and over...
Disable Events...
Sub Worksheet_Change(ByVal Target As Range)
Application.EnableEvents = False
Target.ClearContents
MsgBox "You just changed " & Target.Address
Application.EnableEvents = True
End Sub
hope that helps..