Sounds like a syncronization issue. What version of Exchange are you connecting to? Outlook 2007 will try to find and utilize the CAS server in Exchange 2007 for its free/busy info. If you are connected to Exchange 2003 then it will have to utilize the schedule+/free busy public folder instead. Check your synch issues folder in Outlook. See if there are local or server failures listed in there. That will help you find the source of the problem. When I migrated our organization from Exchange 2003 to Exchange 2007 I had to resolve issues with the public folders and the schedule+/free busy folder which was not being replicated to my exchange 2007 environment. Sounds like you may need to get your exchange admin involved in helping resolve this.