Hi there,
I had once a customer who saw the same behavior with Lookout 4.0.1b51. With those versions of Lookout there is an older version of Logos/Citadel installed and I thought with the latest version of Logos/Citadel it solved the customers issue.
First I would try to upgrade to the lastest version of Logos/Citadel. You can get it through ni.com>Support>Drivers&Updates(Option3)>Search Drivers and Updates>type 'logos' and go to 'Lookout Version 4.0 for Windows 2000/95/98/NT/XP -- Citadel and Time Synchronization Servers'
The readme should explain the installation procedure.
I hope with this update it ack's your remaining alarm in you alarm window - please, let me know.
Hope this helps
Roland