Hello;

Sorry to bring up this old problem, but suddenly the screen flickers when I
click the button to run a relatively simple macro.
The Application.ScreenUpdating = False
does no longer have the effect of suppressing this initial jiggle!!
(I'm assuming that ScreenUpdating defaults back to True when the macro
terminates its execution.)

There're NO timers, NO event procedures, and NO other macros in this wb.

Could someone please shed some light on the possible cause ?? and how to fix
it ?

Here's the simple macro code which works fine apart from the flickering of
the screen when the macro starts.

Sub Spiral_Solver_4()
Dim myCheck As VbMsgBoxResult

'minimize the amount of flashing you see on the screen
   Application.ScreenUpdating = False

' initialize values
 Range("B13") = Range("B14")
 Range("C13") = Range("C14")
 
 Range("D17") = Range("A17")
 Range("D18") = Range("A18")
 Range("D19") = Range("E19")
 Range("J16") = Range("H16")
 Range("F13") = Range("F14")
 
   SolverLoad LoadArea:="$J$20:$J$27"
   SolverOptions MaxTime:=1000, Iterations:=10000, Precision:=0.0001, _
        AssumeLinear:=False, StepThru:=False, Estimates:=2, Derivatives:=2, _
        SearchOption:=2, IntTolerance:=5, Scaling:=False,
Convergence:=0.0001, _
        AssumeNonNeg:=False
   SolverOk SetCell:="$H$10", MaxMinVal:=3, ValueOf:="0", _
       ByChange:="$D$17,$D$18,$D$19,$J$16"

'check if Solver failed
Test = SolverSolve(True)
MsgBox (Test) 'returns 0 or 1 for NO error
             
myCheck = MsgBox("0 or 1 OK." & Chr(10) & "Continue ??", vbYesNo)
   If myCheck = vbNo Then
       Exit Sub
   End If
   
'continue with Solver if successful
   SolverSolve Userfinish:=True
   Solverfinish keepfinal = 1
   Range("A1").Select
   
End Sub

Thank you kindly.
(Excel 2003 SP2, Windows XP)