This article was previously published under Q258584
This article has been archived. It is offered "as is" and will no longer be updated.
NOTE: These procedures only apply if you have installed Outlook with the Internet Mail Only option. To determine your installation type, click About Microsoft Outlook on the Help menu. If you have the Internet Mail Only option installed, you see "Internet Mail Only".
For information about the differences between Microsoft Outlook and Microsoft Outlook Express e-mail clients, click the following article number to view the article in the Microsoft Knowledge Base:
257824 OL2000: Differences Between Outlook and Outlook Express
When you use Outlook in IMO mode and switch quickly between moderately populated folders on an Internet Messaging Access Protocol (IMAP) server, Outlook may stop responding. You may see one of the following messages on the Outlook Status bar:
Updating cached messages
Fetching new headers
Outlook stops responding more frequently when you switch between folders that are heavily populated with e-mail messages.
This problem occurs because there are two threads that have collided and are at a standstill because they are both waiting for the other thread to finish its operation; one of the threads is working with IMAP fetch responses from the server, and the other thread is trying to switch folders.
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.The English-language version of this fix should have the following file attributes or later:
Date Time Version Size File name ------------------------------------------------------ 03/30/2000 12:01a 9.0.3929.0 368,691 pstprx32.dll 04/25/2000 04:24p 3,022 readme.txt
To temporarily work around this problem, wait for all headers and cached information to be updated before you switch folders.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.