How to find the lost 'installed application' - OpenOffice.org Impress

[Ryan Duan <duanpanda@gmail.com>]

Hi,
    I use Debian squeeze, now it cannot find OpenOffice.org-Impress to
open odp and ppt files, but Impress does have been installed, I can
use command "ooffice -impress" to open it.

    I'm sure the following packages are well installed:
openoffice.org, openoffice.org-impress, openoffice.org-gnome.

Details:

1. .odp file handler isn't Impress, .ppt file handler missing, Impress
missing in "installed applications" list.
    Right click .odp file, expect to open it with Impress by default,
but the default handler app becomes "Open with Document Viewer".
Further more, click "Open with other application...", in the
"installed applications" tab, I can find all of "OpenOffice.org"
entries except "OpenOffice.org Impress".

2. In the main menu "Applications -> Office", there are all the
OpenOffice entries except "OpenOffice.org Impress". I didn't remember
when and how I got it lost.

3. The above phenomena occur in my default user - the one created
during the installation of Debian.
    I created a new user with menu "System -> Administration -> Users
and Groups" with the account type being "Desktop User", in the new
user, everything is OK!

4. I tried reinstall or dpkg-reconfigure package
openoffice.org-impress, but no help.

    Does anybody have good idea to help me fix it?

Thanks!

Ryan