This article describes some of the most common reasons that cause Outlook to become unstable, crash, hang or freeze.
If you are experiencing issues with your Outlook, try these items one-by-one and hopefully one of them will help.
Corrupted PST file
By far the most common reason for Outlook crashes, instability and unexplained weird behavior is a corrupted PST or OST file. Microsoft is aware of this issue and provides a tool to fix it – Inbox Repair tool (scanpst). Follow the steps listed in that Microsoft Knowledge Base article to run ScanPST. Run it on all your PST files.
In many cases, ScanPST requires more than one pass to fix a corruption. Run ScanPST repeatedly, until it reports that there are no more errors.
In some cases, a corruption might be so bad that ScanPST is unable to fix it. ScanPST will tell you that there are no more errors, but you would still experience issues. In this case, you should create a new PST file and copy all items from the old PST into the new one. After you do that, close the old PST file (Right-click the top-most folder of the PST, then select “Close”).
Note: You can also use scanPST to check and fix your OST files.
Corrupted OST file
The issue is similar to the one above, it applies to cases when you are using and Exchange email account. For Outlook 2007 and older, Microsoft was shipping an OST Integrity Check tool (ScanOST).
For Outlook 2010, Microsoft suggested exporting OST into a PST, then deleting the OST file and reimporting messages from the PST. It is probably easier to simply run ScanPST, described in the previous section, on your OST file. Alternatively, you can simply delete the OST file, restart Outlook and let it rebuild the OST file. Note: This operation might take a long time if you have a large Exchange mailbox.
Corrupted Profile
Sometimes an Outlook profile might get corrupted. In this case, you have to create a new profile.
Corrupted Outlook Configuration Files
In addition to PST, OST and profiles, Outlook has several other files which might get corrupted. If the above steps did not help, please try renaming outcmd.dat, extend.dat and Frmcache.dat as described in Part 2 of this article.
Misbehaving Add-ins
Running unnecessary add-ins may make Outlook slower and even cause stability issues. Check what add-ins you have installed. You probably have more add-ins installed than you think. Use the following instructions to see what add-ins you have installed and disable the ones you are not using. Leave only the Add-ins you absolutely must have in Outlook.
How to disable addins in Outlook 2010
How to disable addins in Outlook 2007
How to disable addins in Outlook 2003
Keep Windows Up To Date
Regularly use Windows Update to keep your computer up to date with the latest patches and service packs. We recommend that you configure Windows to check for updates automatically.
Hope you found this article useful. If you have additional tips, please share them in comments below.
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