Excel crashes with JIT Debugger Error Message

I created this code for another user. When executed, Excel crashes and restarts with an error message it cannot find the JIT debugger. This does not happen when running other codes. Have done some research on JIT debugger but I am unable to find a fix related to Excel. Any thoughts on this issue?

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
    Dim ThisRow As Integer
    If Target.Column = 3 Then
        ThisRow = Target.Row
        Range("E" & ThisRow).Value = Range("C" & ThisRow).Value + Range("E" & ThisRow).Value
        Range("C" & ThisRow).ClearContents
    End If
End Sub