Enabling dri using the ati r128 driver displays a highly distorted screen. 
Produces no readable text or menus.  Two dots on the first line of the screen,
one in the top left and one in the middle.  Mouse cursor moves around the full
screen, but whem clicked, keyboard locks and cursor cannot be returned to
pre-clicked state, but still moves.  Artifacts of previous framebuffer images
are shown on the bottom half of the screen as well if UseFBDev is set.  Xorg log
showed that DRI had successfully loaded and be started.  Log file ends with th
following two lines each time:

(EE) R128(0): R128CCEWaitForIdle: (DEBUG) CCE idle took i = 1025
(EE) R128(0): Idle timed out, resetting engine...

With DRI disabled, the screen appears normal and log file contains only the
folling error:

(EE) R128(0): V_BIOS address 0x0 out of range
(--) R128(0): Chipset: "ATI Rage 128 VR RL (AGP)" (ChipID = 0x524c)

Narrowed the problem to DRI by disabling other modules/options, none of which
had any other effect.

# This file was generated by Xorgautoconfig v0.2.2.
Section "ServerLayout"
        Identifier      "X.Org Configured"
        Screen          0  "Screen0" 0 0
        InputDevice     "Mouse0" "CorePointer"
        InputDevice     "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"
# RgbPath is the location of the RGB database.  Note, this is the name of the
# file minus the extension (like ".txt" or ".db").  There is normally
# no need to change the default.


# ModulePath can be used to set a search path for the X server modules.
# The default path is shown here.


# Multiple FontPath entries are allowed (which are concatenated together),
# as well as specifying multiple comma-separated entries in one FontPath
# command (or a combination of both methods)

# For X Font Server support, uncomment this and comment the other FontPaths
# Note that this is not required for most configurations
#       FontPath        "unix/:-1"
        FontPath        "/usr/share/fonts/encodings/"
        FontPath        "/usr/share/fonts/cyrillic/"
        FontPath        "/usr/share/fonts/75dpi/"
        FontPath        "/usr/share/fonts/75dpi/:unscaled"
        FontPath        "/usr/share/fonts/misc/"
        FontPath        "/usr/share/fonts/Type1/"
        FontPath        "/usr/share/fonts/100dpi/"
        FontPath        "/usr/share/fonts/100dpi/:unscaled"
        FontPath        "/usr/share/fonts/util/"
        FontPath        "/usr/share/fonts/TTF/"
EndSection

Section "Module"
        Load    "extmod"
#####
#
# 
# DRI BREAKS X
#
#       Load    "dri"
#
#####
        Load    "dbe"
        Load    "record"
        Load    "glx"
        Load    "type1" 
        Load    "freetype"
        Load    "fbdevhw"
EndSection

Section "Extensions"
#       Option "Composite"      "Disable"       # Experimental
EndSection

Section "ServerFlags"
        Option  "blank time"    "10"    # 10 minutes
        Option  "standby time"  "20"
        Option  "suspend time"  "30"
        Option  "off time"      "60"
### Uncomment this Server flag if X should not change resolutions.
### This is useful if mode changing crashes / corrupts the X server
#       Option  "DisableVidModeExtensions"
EndSection

Section "InputDevice"
        Identifier      "Keyboard0"
        Driver          "kbd"
# Change "XkbModel" to "macintosh_old" if you are using
# the deprecated adb keycodes.
        Option          "XkbModel"      "pc105"
        Option          "XkbLayout"     "us"
        Option          "XkbOptions"    "compose:rwin"
### Uncomment this if your layout uses nodeadkeys
        #Option         "XkbVariant"    "nodeadkeys"
EndSection

Section "InputDevice"
        Identifier      "Mouse0"
        Driver          "mouse"
        Option          "CorePointer"
        Option          "Protocol"       "IMPS/2"
        Option          "Device"         "/dev/input/mice"
        Option          "ZAxisMapping" "4 5"
EndSection

Section "Monitor"
        Identifier      "Monitor0"
        UseModes        "Modes0"
        ModelName       "Monitor Model"
        Option          "DPMS"
        HorizSync       60-60
        VertRefresh     60-75
EndSection


Section "Modes"
        Identifier      "Modes0"

        # Generated
        # D: 78.740 MHz, H: 60.015 kHz, V: 75.019 Hz
        Modeline "1024x768" 78.740 1024 1056 1152 1312  768 769 772 800  +HSync
+VSync
EndSection

Section "Device"
        Identifier      "Card0"
        ### Available Driver options:
        Option "DMAForXv"       "true"  # Use DMA for XV, reduces CPU usage
                                        # Can cause stability problems
        #Option "SWcursor"      "false" # Use Software Cursor
        #Option "NoAccel"       "false" # Disable Hardware Acceleration
        Option "Display"        "CRT"   # Display mode for devices which
                                        # support Flat Panels.  Modes:
                                        # "FP" - Use Flat Panel
                                        # "CRT" - Use CRT
                                        # "Mirror" - Use both FP and CRT
        ### See "man r128" for additional options

        ### Warning: If your r128 has less than 10MB of ram, you will only be
        ###          able to use dri in 16bit color.
        Option  "UseFBDev"      "False"
        Driver  "r128"
        BusID   "PCI:0:16:0"
EndSection

Section "Screen"
        Identifier      "Screen0"
        Device          "Card0"
        Monitor         "Monitor0"
        DefaultDepth    16
        SubSection "Display"
                Depth           8
                Modes           "1024x768"
        EndSubSection
        SubSection "Display"
                Depth           16
                Modes           "1024x768"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1024x768"
        EndSubSection
EndSection


###### 
#
# DRI BREAKS X
#
#
# Section "DRI"
#       Group 0
#       Mode 0666
# EndSection
#


Full log of Xorg was on pastebin but is now gone.  Problem can be reproduced to
gain a full log if needed.  Also installing a stable version of X to try to
replicte the problem in it as well.