I'm using IE8 and Firefox 10.
With IE8 (official browser in the office), making a change in activities, leads to freeze activity screen. It was impossible to select another activity, you must quit IE8, flush the cache and reconnect.
Here is the error reported by IE8 :
Détails de l’erreur de la page Web
Agent utilisateur : Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; InfoPath.1; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; MS-RTC LM 8; .NET4.0C; .NET4.0E)
Horodateur : Thu, 16 Feb 2012 12:59:12 UTC
Message : Cet objet ne gère pas cette action.
Ligne : 1102
Caractère : 2
Code : 0
URI : [url].../view/js/projector.js[/url]