Here is a message which was appearing in my syslog file until I solved the problem :

[drm] Initialized drm 1.1.0 20060810
mtrr: type mismatch for e0000000,10000000 old: write-back new: write-combining

MTRR stands for Memory Type range registers. Its a new feature available in the latest Intel processors.It is a new way of partitioning and managing memory resources in your system.There are two solutions for using the right values for mtrr.
The first one is to add this option to your grub command line :  enable_mtrr_cleanup mtrr_spare_reg_nr=1
The second one is to recompile your current kernel and choose the value 1 instead of 0 for MTRR cleanup enable value (0-1) while issuing the command make menuconfig.

I chose the first solution and I do not get any error messages no more :

dmesg |grep mtrr
[    0.000000] MTRR default type: uncachable
[    0.000000] MTRR fixed ranges enabled:
[    0.000000] MTRR variable ranges enabled:
[    0.000000] original variable MTRRs
[    0.000000] Found optimal setting for mtrr clean up
[    0.000000] New variable MTRRs
[    0.000000] Kernel command line: root=/dev/sda2 ro quiet enable_mtrr_cleanup mtrr_spare_reg_nr=1

cat /proc/mtrr
reg00: base=0×000000000 (    0MB), size= 2048MB, count=1: write-back
reg01: base=0×080000000 ( 2048MB), size= 1024MB, count=1: write-back
reg02: base=0x0bdd00000 ( 3037MB), size=    1MB, count=1: uncachable
reg03: base=0x0bde00000 ( 3038MB), size=    2MB, count=1: uncachable
reg04: base=0x0be000000 ( 3040MB), size=   32MB, count=1: uncachable
reg05: base=0x0e0000000 ( 3584MB), size=  256MB, count=2: write-combining

For more information :

http://en.gentoo-wiki.com/wiki/MTRR


https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/314928


https://help.ubuntu.com/community/AspireOneDiscussion


http://www.phoronix.com/forums/showpost.php?p=74238&postcount=5


http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/en-US/Reference_Guide/s2-proc-mtrr.html

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