Earlier today I was troubleshooting a problem with sent items being displayed twice in my Outlook 2010 mail client. My configuration is definitely not standard and I have had issues before with some accounts putting two sent items in the same folder and some not however today all of the email being sent was showing up in my sent items folder twice. Initially I figured it would be a corrupt Outlook Rule or something similar but when I took at the list of my accounts in the left navigation bar within Outlook I noticed that one of my IMAP accounts was opened twice. I attempted to close one of the instances of the IMAP account without any luck. After messing around for a bit I was able to come up with a solution which is detailed below.
Recently my laptop crashed while Microsoft Outlook was open which caused one of the open .PST files to become corrupted. The PST file that was corrupted was for a Gmail account that was synced with Google Gmail via IMAP. The error message that popped up when attempting to expand the folders is described below and then displayed in the image below the explanation.
Error: The set folders cannot be opened. Errors have been detected in the file C:\Documents and Settings\user\Local Settings\Application Data\Microsoft\Outlook\OutlookAccount@gmail.com-00001.pst. Quit Outlook and all mail enabled applications, and then use the Inbox repair tool (Scanpst.exe) to diagnose and repair erros in the file. For more information about the Inbox repair tool, see Help.