Certain web pages on Mozilla cause my screen to go funny.

[Adam Funk <a24061@yahoo.com>]

Certain web pages cause my screen to "go funny" with horizontal lines
for a few seconds, then leave it looking ugly until I log out of GDM
and back in again.  This happens only with Firefox and Mozilla; I can
look at the same pages in Konqueror and Galleon.  It used to happen
occasionally on slashdot.org (usually on Apple-related pages, I think)
but not www.theregister.co.uk is giving me trouble.  I use XFCE4 but
I've had the same problem in GNOME.

Here's a screenshot of the after-effects.
http://www.ducksburg.com/misc/snapshot12.png

Below is some information I think might be relevant.  Please ask for
anything else that might help.

Thanks,
Adam

Package list:
ii  gdm                                          2.4.4.7-3     
ii  mozilla                                      1.6-5    
ii  mozilla-browser                              1.6-5    
ii  mozilla-locale-de-at                         1.6-4    
ii  mozilla-mailnews                             1.6-5    
ii  mozilla-psm                                  1.6-5    
ii  mozilla-xft                                  1.6-5         
ii  xfree86-common                               4.3.0.dfsg.1-8
ii  xfce4                                        4.0.5-1 
ii  xfce4-artwork                                0.0.4-3 
ii  xfce4-datetime-plugin                        0.2-3
ii  xfce4-diskperf-plugin                        1.3-3
ii  xfce4-iconbox                                4.0.6-1
ii  xfce4-mcs-manager                            4.0.6-1
ii  xfce4-mcs-plugins                            4.0.6-1
ii  xfce4-mixer                                  4.0.6-1
ii  xfce4-panel                                  4.0.6-1
ii  xfce4-session                                0.1.3+20031213-5
ii  xfce4-systemload-plugin                      0.3.3-4
ii  xfce4-systray                                4.0.6-1
ii  xfce4-themes                                 4.0.6-1
ii  xfce4-toys                                   4.0.6-1
ii  xfce4-trigger-launcher                       4.0.6-1
ii  xfce4-utils                                  4.0.6-1 

Excerpt from /etc/X11/XF86Config-4

Section "Device"
        Identifier      "S3 SAVAGE4 PRO/32MB PCI"
        Driver          "savage"
        Option     "SWCursor"  "on"
        Option     "HWCursor"  "off"
EndSection

Section "Monitor"
        Identifier      "DELL P790"
        HorizSync       30-92
        VertRefresh     50-150
        Option          "DPMS"
EndSection