Control Panel-Folder Options-View-File types. Select the extension and press advanced.

--�
Milly Staples [MVP - Outlook]

Post all replies to the group to keep the discussion intact. All
unsolicited mail sent to my personal account will be deleted without
reading.

After furious head scratching, Tom asked:

| I don't want to be prompted "You should only open attachments from a
| trustworthy source ..." warning in Outlook 2007 on Vista when trying
| to open Office 2007 and 2003 .doc, .docx, xls, xlsx, and .pdf files.
|
| Unfortunately, the "Always ask before opening this file" checkbox is
| disabled, so I can not remove the checkmark on it.
|
| Is there a way to enable the checkbox?