How to end repeating Makro

Hi all

I have done a makro that uses the calculation command (F9).
Why: Because i want to make an countdown from an specified time in the future from the todays time in hour:minute:secons.

heres the sub

Sub uppdaternr2()
'
' uppdaternr2 Makro
' Makrot inspelat 2005-04-29 av ppalm
'
Calculate


Application.OnTime Now + TimeValue("00:00:01"), "uppdaternr2"


End Sub

Everything works but but.. when i trie to exit the worksheet it just pops up again. to exit i have to klick on the close excel program button. How can i make the sub stop???

Perhaps i can use somother command to make the countdown every second.
Anyone has a sugesstion ??

I´m getting cracy know been lookink i vba help but no answers
plz anybod