Comment 20 for bug 353996

Well. Finally I found the way to make works it.

I did change the /etc/X11/xorg.conf file, Now it's working fine

Let me show you: with this configuration the system is working like with Intrepid.

Section "Device"
 Identifier "Configured Video Device"
 Boardname "ATI Radeon"
 Busid "PCI:1:0:0"
 Driver "radeon"
 Screen 0
 Vendorname "ATI"
 Option "MergedFB" "off"
 Option "AccelMethod" "EXA"
 Option "EXANoComposite" "false"
 Option "FBTexPercent" "50"
 Option "MigrationHeuristic" "greedy"
 Option "DRI" "true"
 Option "GARTSize" "256"
 Option "AGPMode" "4"
 Option "Colortiling" "On"
EndSection

Section "DRI"
 Mode 0666
EndSection

Section "ServerLayout"
 Identifier "Default Layout"
 screen 0 "Default Screen" 0 0
 Option "AIGLX" "true"
EndSection

Section "Extensions"
 Option "Composite" "Enable"
EndSection

Section "Monitor"
 Identifier "Configured Monitor"
EndSection

Section "Screen"
 Identifier "Default Screen"
 Monitor "Configured Monitor"
 Device "Configured Video Device"
EndSection