While experienced Outlook users have troubleshooting Outlook down pat, newer users often don't know where to begin so they start by uninstalling and reinstalling Office or Outlook. Because most problems are caused by corruption in the user configuration files and registry entries or by third party add-ins, and these are preserved during a reinstall, uninstalling and reinstalling won't help much. Along with configuration settings and add-ins, corrupt items in the mailbox may cause problems and these are fixed by either starting Outlook using special commands or identifying and deleting the item.

When Outlook crashes and wants to send a crash report back to Microsoft, look at the report's details before sending it. Within the first few lines it should say something along the lines of 'file1 caused an exception in file2'. If you aren't sure what program the files belong to, use Windows search to find the files then check the file's properties to identify the application that installed it. If the file belongs to an add-in, disable the add-in.

Tip: Unless your company has a policy against sending crash reports, you should always send them. It helps Microsoft identify problem areas and the next service pack might include a fix for it.

Are Updates waiting for a Reboot?

Before doing anything, see if any updates are waiting for a reboot to be installed. Look on the Shutdown menu; if it lists Restart and Install Updates, install the updates and reboot. Waiting updates can cause weird and annoying behaviors, usually things like the mouse or menus not working right or applications running slow. They can also make it seem like your profile and data files are corrupt.
 

Safe Mode

Begin your troubleshooting by starting Outlook using the /safe switch. This loads Outlook without the extras such as custom toolbars and add-ins. If it works, it's unlikely that a reinstall or detect and repair will help, since the problem is not with Outlook's program files and detect and repair doesn't replace the configuration files.

To start Outlook using the /safe switch, close Outlook and verify it's closed in Task Manager, then hold Ctrl as you click on the Outlook icon to start in Safe mode.

You can also use the /safe command line switch:

Open the Run command using Windows key + R then type or paste:

Outlook.exe /safe

New Profile

If starting in Safe mode helped, create a new Outlook profile. Don't delete your current profile and don't copy it, just create another one using a new name. When you copy a profile and it's corrupt, you'll only succeed in copying the corruption to the new profile. Another mistake people often make is deleting the profile then creating a new one using the same name. Since several of the configuration files are named for the profile, it may reuse them in the new profile.

If you need instructions to create a new profile, I have instructions at How to Create a New Profile

If you use multiple e-mail accounts, you only need to set up one account to test the profile. If the new profile works, it means a file or registry entry associated with the old one is corrupt. At this point, you can either delete the old profile and use the new one or try to figure out where the problem is with the old profile. If you decide to keep the new profile, you can add the *.pst from the old profile to your new profile, setting it as the default delivery location if desired.

When you use several e-mail accounts, continuing to troubleshoot is often easier than recreating all of the accounts. Locate and delete or rename the configuration files associated with your profile, starting with the SRS and outcmd.dat files. Outlook will recreate fresh new ones the next time it runs.

Look in C:\Users\username\AppData\Roaming\Microsoft\Outlook (Win7 & Vista) or C:\Documents and Settings\username\Application Data\Microsoft\Outlook (WinXP) for the following files associated with your profile:

• *.NK2 (nickname or autocomplete cache) in Outlook 2003 or 2007, *.nick in older versions
• *.SRS (send and receive settings)
• *.XML (Navigation Pane in OL2003 and up) or *.FAV (Outlook Bar)
• Outcmd.dat (toolbar customizations, shared by all Outlook profiles; Outlook 2007 and older)
• Outlprnt (print configurations)
• VBA files

If you upgraded to Outlook 2003 or above, delete any *.FAV files you find in that folder. It's not used by Outlook 2003 or above and may introduce problems with the Navigation bar settings.

Scanpst

If you suspect the data file is corrupt, rename the *.pst or *.ost and allow Outlook to create a new one. If Outlook works, run scanpst.exe on the old pst file or export the data to the new pst. See Where are my Outlook files? if you need help finding the pst files.

Note that by default, Windows hides some of your user profile folders from you. Change the settings in Windows Explorer's Tools, Folder Options, View tab to show hidden files and folders and remove the check from hide system files or used the advanced search options to search hidden and system folders.

How to use Scanpst.exe to repair Microsoft Outlook data files

Addins

Com add-ins are frequent cause of problems in Outlook that won't be solved by new profiles or Detect and Repair. Sometimes Outlook is smart enough to disable add-ins that are causing problems. These are added to the Disabled Add-ins list in the Help, About Microsoft Office Outlook, Disabled Items dialog. When it doesn't, or when the problem is more of an annoyance than a crash, go to Tools, Options, Other, Advanced Options, COM add-ins and uncheck all add-ins and test Outlook. If it works correctly, re-enable the add-ins one at a time and test again.

Examples of the annoyance type problems caused by add-ins that won't cause Outlook to disable the add-in include:

• Outlook won't exit - ActiveSync or another application is accessing the mailbox store.
• Odd behaviors, such as keyboard shortcuts don't work, the clipboard clears automatically, etc.
• Mail won't send if you click on the Outbox folder.

Note that not all add-ins are listed in the com add-in dialog. You'll need to look in the registry, at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\Add-ins. A loadbehavior value of 3 means the add-in loads when Outlook starts. Change the value to 1 and see if the problem goes away.

Repair

When the problem isn't solved by a new profile or by disabling add-ins, use Repair.

In Outlook 2007 and newer, run Repair from Control Panel's Programs and Features

In older versions, it's on the Help menu. This has the same effect as uninstalling and reinstalling but is much faster. If you use an older version of Outlook that doesn't have Detect and Repair, rerun setup. You don't need to uninstall it first.

Command lines

Items stored in the mailbox can become corrupt and may cause Outlook to crash or hang. To help solve this problem, Outlook offers several command line switches you can use to clean the hidden items from your mailbox. Keep in mind that while many of the switches are harmless, others will delete your customizations. To learn more about command line switches Outlook supports, see Outlook's Command Line Switches

When a visible item, such as a message or an appointment, is corrupt you'll need to identify the item through trial and error and delete it.

Corrupt views cause problems when you try to view folders but usually don't cause Outlook to crash. To repair, you can either start Outlook using the /cleanviews switch, which deletes and resets all views, including any custom views you created, or try deleting or resetting just the currently selected view. To do this, open the Define views dialog. You'll find it at the end of the list of views on the Select views tool on the Advanced toolbar. Note the name of the current view before opening the Define Views dialog and reset or delete it after you open the dialog. If this fails, you'll need to use the /cleanviews switch.

Forums

If you've tried all of the above and are still having problems, you can ask for help in the Microsoft Outlook forums. Be sure to include your Outlook version and types of mail accounts in your profile - this can be immensely helpful to people trying to help you.

Outlook Forums | Microsoft Answers forum