It would help to know if this is an ISP pop3 account downloading to a pst, or an exchange account connecting by MAPI. If a pst you can run scanpst against the pst file. If that does not resolve you may need to create a new outlook profile and migrate the mail into the new profile. You can also try running a repair install. Go into add/remove programs and for microsoft office choose change, then choose repair. If an exchange mailbox try removing and re-adding your profile, you will not need to migrate mail in that case. The more details you provide the more detailed and helpful answers we can provide. Please tell us what troubleshooting you have done as well. thanks.