Intel problem with dri

[ChIIph]

Hi you all, I'm having some troubles with DRI and an Intel card...
The problem came up when I installed Maya, a 3d modelling/rendering/etc 
software, and when a subwindow or a menu overlaps the 3d viewport, it becomes 
all black, and when I "force" the viewport to refresh, doing something like 
zooming in or out, it shows me the actual scene in the viewport.

How do I came to the conclution that it was DRI the problem? well, DRI or GLX 
actually... I was playing with xrandr, and an external monitor (I have a 
laptop MSI VR600) and in order to have the panned screens I've got to set a 
virtual resolution over the 2048x2048 that Intel supports with DRI (or so I 
read...), and when I openned Maya with this settings it's a little bit slow, 
but it works fine...

Any ideas what is happening here?
Thanks!

Some info:
lspci | grep -i display:
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS, 943/940GML 
Express Integrated Graphics Controller (rev 03)

cat /etc/X11/xorg.conf:
Section "ServerLayout"
        Identifier     "X.org Configured"
        Screen      0  "Screen0" 0 0
        InputDevice    "Mouse0" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"
        InputDevice    "tablet" "AlwaysCore"
        Option "AllowMouseOpenFail" "true"
EndSection

Section "Files"
        RgbPath      "/usr/share/X11/rgb"
        ModulePath   "/usr/lib/xorg/modules"
        FontPath     "/usr/share/fonts/misc/"
        FontPath     "/usr/share/fonts/TTF/"
        FontPath     "/usr/share/fonts/OTF"
        FontPath     "/usr/share/fonts/Type1/"
        FontPath     "/usr/share/fonts/100dpi/"
        FontPath     "/usr/share/fonts/75dpi/"
EndSection

Section "Module"
        Load  "glx"
        Load  "extmod"
        Load  "xtrap"
        Load  "record"
        Load  "GLcore"
        Load  "dbe"
        Load  "dri"
        Load  "freetype"
        Load  "type1"
        Load  "v4l"
EndSection

Section "InputDevice"
        Identifier  "Keyboard0"
        Driver      "kbd"
        Option      "XkbRules" "xorg"
        Option      "XkbModel" "pc104"
        Option      "XkbLayout" "es"
EndSection

Section "InputDevice"
        Identifier  "Mouse0"
        Driver      "mouse"
        Option      "Protocol" "Auto"
        Option      "Device" "/dev/input/mice"
        Option      "ZAxisMapping" "4 5 6 7"
EndSection

Section "InputDevice"
        Identifier  "tablet"
        Driver          "wizardpen"
        Option          "Device"        "/dev/wizardpen"
        Option          "TopX"          "1899"
        Option          "TopY"          "3692"
        Option          "BottomX"       "30977"
        Option          "BottomY"       "31165"
        Option          "MaxX"          "30977"
        Option          "MaxY"          "31165"
EndSection

Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "CMO"
        ModelName    "1526"
 ### Comment all HorizSync and VertRefresh values to use DDC:
        HorizSync    31.5 - 82.0
        VertRefresh  58-61
        Modeline "1280x800_60.00"  83.46  1280 1344 1480 1680  800 801 804 
828  -HSync +Vsync
        Modeline "1680x1050_60.00"  147.14  1680 1784 1968 2256  1050 1051 
1054 1087  -HSync +Vsync
        Option       "DPMS"
EndSection

Section "Monitor"
        Identifier   "Monitor1"
        VendorName   "CMO"
        ModelName    "1526"
        Modeline "1280x1024_60.00"  108.88  1280 1360 1496 1712  1024 1025 
1028 1060  -HSync +Vsync
        Option       "DPMS"
        Option       "CRT"
EndSection

Section "Device"
        Identifier  "Card0"
        Driver      "intel"
        VendorName  "Intel Corporation"
        BoardName   "Mobile 945GM/GMS, 943/940GML Express Integrated Graphics 
Controller"
        BusID       "PCI:0:2:0"
        Option "DRI" "true"
EndSection

Section "Screen"
        Identifier "Screen0"
        Device     "Card0"
        Monitor    "Monitor0"
        SubSection "Display"
                Viewport   0 0
                Depth     1
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     4
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     8
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     15
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     16
                #Virtual              2560 1024
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     24
                #Virtual              2560 1024
        EndSubSection
EndSection

Section "Screen"
        Identifier "Screen1"
        Device     "Card0"
        Monitor    "Monitor1"
        SubSection "Display"
                Viewport   0 0
                Depth     16
                #Virtual              2560 1024
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     24
                #Virtual              2560 1024
        EndSubSection
EndSection

Section "DRI"
    Mode 0666
EndSection