When you install Microsoft Office 2003 Service Pack 3 (SP3), and then you try to use Microsoft Office Outlook 2003 to open an attachment that has one of the file name extensions that are listed in the "Cause" section, the attachment does not open.

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This behavior occurs because the following file name extensions have been added to the blocked file types in Office 2003 SP3.

Level 1 file types added as blocked by Outlook 2003 SP3

File extension	File type
.der	DER Encoded X509 Certificate File
.gadget	Windows Vista Gadget
.msh	Microsoft Shell
.mshxml	Microsoft Shell
.msh1	Microsoft Shell
.msh1xml	Microsoft Shell
.msh2	Microsoft Shell
.msh2xml	Microsoft Shell
.plg	Developer Studio Build Log
.ps1	Windows PowerShell
.ps1xml	Windows PowerShell
.ps2	Windows PowerShell
.ps2xml	Windows PowerShell
.psc1	Windows PowerShell
.psc2	Windows PowerShell
.xnk	Exchange Public Folder Shortcut

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These files may contain executable code that could potentially harm your computer. Therefore, these attachments have been blocked in Outlook 2003 SP3.

For information about the file types that are restricted or disabled in Outlook 2003, visit the following Microsoft Web site: For more information, click the following article number to view the article in the Microsoft Knowledge Base: For more information about how to obtain the latest Office 2003 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

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