Excel Flickering & text scroll issues

[Trick]

I am experiencing a strange excel issue whereby the sheet seems to refresh itself numerous times, this is noticeable when i have an image inserted into the sheet, and this flickers and looks as though its moving - very annoying.
Also, when i scroll down a sheet, the text often disappears or scrambles up - only visual effect of course, but all the same very strange.

I thought it was due to the Macro issue when running VBA macro code. So i checked the macros, and they included this text:

 
Sub SlowWithFlicker()
Dim rCell As Range
    For Each rCell In Range("A1:A15000")
        rCell.Select
    Next rCell
End Sub

Sub FastWithNoFlicker()
Dim rCell As Range
    Application.ScreenUpdating = False
        For Each rCell In Range("A1:A15000")
            rCell.Select
        Next rCell
    Application.ScreenUpdating = True
End Sub

This didnt make a difference, so i removed all macros, and still does it.
Any suggestions? this has never occurred during the 10 years ive been using excel.