Probably the biggest problem I've had with Microsoft Outlook over the last decade is with my Outlook Profile getting slightly corrupted, preventing me from closing open "archive" PST files. When you attempt to close the PST, you'll see the following message:
Error: The operation failed. An object could not be found.
This is actually caused by a Registry corruption to the Outlook profile that is in use. Microsoft recommends creating a new profile, but that makes you re-create all your E-mail Accounts and you lose your rules, autocomplete addresses, etc. You can back up your rules, but re-creating a profile is a bit of a pain if you have a complex Outlook configuration.
Today I ran into this problem again. I was migrating all my archived "Deleted Items" for 2007 to a new PST so I could permanently archive the file. After moving all the files, I wanted to compress my archived "Deleted Items" folder but couldn't because I was getting this error message.
Since I really didn't want to re-create my profile, I went out searching for a tool that might be able to clean up my profile for me. Fortunately after a few minutes of Googling, I came across CodeTwo PST Ghostbuster.
This program worked like a charm to clean up my profile. You'll want to use the "Backup" feature before you attempt deleting a PST—just to make sure you can restore things if something goes awry.
If I could make an improvement to the program, it would be for the list of PST files to delete to be a select box of attached PST files instead of having to type the name of the PST folder into the text box. However, the program worked as advertised and saved me lots of time since I didn't have to migrate to a new profile.