refer this : )

Your user may be having problems opening ANY Office attachments. If this is the case then this is caused by Outlook trying to use a temporary folder to which the use doesn't have write rights. To fix this you'll need to add the following lines to the registry:

[HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Outlook\Security]
"Level"=dword:00000003
"OutlooksecuretempFolder"="temp folder path"

Replace the "temp folder path" with the path to the users temp folder (e.g. c:\documents and settings\username\local settings\temp) or other suitable (and accessible!) location.

If you don't fancy hacking the registry manually, copy the above into notepad, edit the path (keeping the quotes around it), add

Windows Registry Editor Version 5.00

in as a first line and save it with a .reg file extension. You can now enter the lines into the registry by double-clicking the file when logged on as the user.  

@@@ from http://techrepublic.com.com/5208-11192-0.html?forumID=42&threadID=174815

alex 님이 쓰신 글 :
: Does any one has anyidea how to open attachment file on outlook?
: I have my own "rpt" file viewer. it works fine standalone but not work on outlook.
: Outlook shows it as a correct icon but when i double click. it say "can't find file path".
: Please help..