UnCall a sub routine

Please post a copy of Flashback

Ok you are asking the user to select a cell to stop the macro.

So at the top of your module declare a public variable

Public StopFlag as Integer

Sub Auto_Open()
StopFlag = 0
End Sub

Now you need to Set the Stop Flag

so right click on the sheet name at the bottom of excel and select view code

paste this code there.

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
StopFlag = 1
End Sub

Now modify your code .

Sub FlashBack()

 Dim newColor As Integer
 Dim myCell As Range
 Dim x As Integer
 Dim fSpeed

StopFlag = 0

 Set myCell = ActiveCell
 Application.DisplayStatusBar = True
 Application.StatusBar = "... Select Cell to Stop and Edit or Wait for Flashing to Stop! "
 newColor = 27
 fSpeed = 0.5
 Do Until x = 20

 DoEvents
 Start = Timer
 Delay = Start + fSpeed
 Do Until Timer > Delay

If StopFlag = 1 then exit Sub

 DoEvents
 myCell.Interior.ColorIndex = newColor
 Loop
 Start = Timer
 Delay = Start + fSpeed
 Do Until Timer > Delay

If StopFlag = 1 then exit Sub

 DoEvents
 myCell.Interior.ColorIndex = xlNone
 Loop
 x = x + 1
 Loop
 Application.StatusBar = False
 Application.DisplayStatusBar = Application.DisplayStatusBar
 End Sub

The selection change macro is sheet specific

so put it in the sheet where you want it to act.