For weeks, I've been plagued with flaky performance by Outlook 2007, the worst of which was it crashing when I close a calendar reminder. This is apparently a not-uncommon problem and there are plenty of recommendations online for things to check. None of those solved my problem. I recently posted a thread about a Microsoft resource for troubleshooting Outlook problems. One of their tools helped identify the cause. I never would have found it because it seems totally unrelated. Check this if nothing else works. The problem was the virus-checker add-in. In my case, it was a module from GFI Software that I believe they sell to various other software companies for incorporation. The actual file was SBAMOutlook.dll. On other computers experiencing Outlook problems, if this file is being used, disable it and see if the problem goes away. But the cause may not necessarily be this particular file. The take-away is to investigate the Outlook add-ins, particularly those from third parties, even if the purpose of the add-in seems totally unrelated to the problem.