We are using Exchange 2000(w/sp3) with Office XP Pro. We can see each other's Calendar information except a couple of users. What I found was those 2 users's Outlook did not have "permissions" tab(Calendar - Properties) even though every user had same hardware and software. Let's say, Calendar for user1 with PC1 and user2 with PC2 are not accessible. Using PC3, I logged in as user1 or user2 and set the permissions just like others. Still Calendar for user1 and user2 are NOT accessible. Shed some lights!