xfree86-dri

Hello

I've got Fedora Core 1
1. I launch xscreensaver-demo
2. Choose Atlantis screensaver.
3. Change some settings
4. Press Preview Button
5. Sometimes it works but sometimes
it tells me

Xlib: extension "XFree86-DRI" missing on display ":0.0"

here is the snippet of /etc/X11/XF86Config

.............
<http://www.opengl.org/discussion_boards/ubb/Forum4/HTML/001152.html>Section "Module"

# This loads the DBE extension module.

   Load        "dbe"      # Double buffer extension

# This loads the miscellaneous extensions module, and disables
# initialisation of the XFree86-DGA extension within that module.
   SubSection  "extmod"
#      Option    "omit xfree86-dga"   # don't initialise the DGA extension
   EndSubSection

# This loads the Type1 and FreeType font modules
   Load        "type1"
   Load        "speedo"
   Load        "freetype"
#    Load    "extmod"
  # Load        "xtt"

# This loads the GLX module
   Load       "glx"
# This loads the DRI module
   Load       "dri"

EndSection
...................

what might be the problem?

Thank you

Vano