This is from MS Off 2k3 help;
By default, Microsoft Outlook blocks potentially unsafe attachment files (such as .bat, .exe, .vbs, and .js) that can contain viruses. You cannot see or access the attachments. Your Inbox will display the paper clip icon in the Attachment column to let you know that the message has an attachment, and you will see a list of the blocked attachment files in the InfoBar at the top of your message. If you try to open the attachment by right-clicking the item, View Attachments will not appear on the shortcut menu. If you need to use files, such as .exe files, that were sent to you from others, have the sender post the files to a network share or to a Web share that you can access.
Now, the MS website says to BLOCK attachments;
Outlook 2003
Follow these steps, and then quit Registry Editor:
Click Start, click Run, type regedit, and then click OK.
Locate and then click the following key in the registry:
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Security
On the Edit menu, point to New, and then click String Value.
Type Level1Add, and then press ENTER.
On the Edit menu, click Modify.
Type <file_name_extensions>, and then click OK.
Notefile_name_extensions is a list of the attachment file name extensions. Each attachment file name extension is separated by a semicolon. For example, type .zip; .gif if you want to block both .zip and .gif files from appearing in the e-mail message as an attachment.
So delete this completely if it exists and do the above with Level1Remove
It "should" work.
Iain