Beginning with Outlook 2003 SP2, users can work with most .oft form templates files only by opening the template from the Tools | Forms | Choose Form dialog, browsing for User Templates in File System.
The article at http://support.microsoft.com/?id=907985 explains this change in more detail, suggests best practices, and provides registry keys that can return Outlook 2003 to the older, less secure behavior.

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I have created a custom form based on the Appointment form for a client
> that is
[quoted text clipped - 5 lines]
>
> What can cause to this problem?
Yakov.Yoffe@gmail.com - 26 Apr 2006 13:30 GMT
Thanks.
But this Outlook 2003 browse dialog window does not have "Look in"
combobox to choose "User Templates in File System".
Ken Slovak - [MVP - Outlook] - 26 Apr 2006 14:50 GMT
Tools, Forms, Choose Form...
Look at the top of the dialog, there should be a drop-down control. If you
are using Exchange it will initially point to Organizational Forms Library.
Click the arrow there and select the option Sue mentioned.

Signature
Ken Slovak
[MVP - Outlook]
http://www.slovaktech.com
Author: Absolute Beginner's Guide to Microsoft Office Outlook 2003
Reminder Manager, Extended Reminders, Attachment Options
http://www.slovaktech.com/products.htm
> Thanks.
> But this Outlook 2003 browse dialog window does not have "Look in"
> combobox to choose "User Templates in File System".