Hi, I have a very baffling issue. The client is running XP Pro and Outlook 2010. When some accounts access a public calendar Outlook becomes very sluggish (almost unusable) and the CPU usage jumps to 70-90%. When you select mail folders or some other object the CPU usage immediately drops. Even a blank calendar that was just created exhibits this behavior. Even more baffling is that if you login to the same machine under a different account the same set of steps won't repro the problem. Neither the server or the workstation have errors or warnings that yield any clues. There are the no apparent performance issues on the server while accessing the public calendar. The Exchange Server is 2007 running on SBS 2008. Regards, CS