*ERROR* EDID checksum is invalid, remainder is 26 - bad monitor frequence

[debecio]

Hello, I have this error in my dmesg. And my external monitor go to max vsync of 60hz (it support 85HZ).
My hardware is eeepc with intel Intel GMA 3150 (driver is i915) on debian squeeze with:

ii  libdrm-intel1                        2.4.23-0.0                           Userspace interface to intel-specific kernel DRM services -- runtime
ii  xserver-xorg-video-intel             2:2.13.0-5                           X.Org X server -- Intel i8xx, i9xx display driver
ii  xorg                                 1:7.5+8                              X.Org X Window System
ii  xserver-xorg                         1:7.5+8                              the X.Org X server
ii  xserver-xorg-core                    2:1.7.7-10                           Xorg X server - core server

Kernel 2.6.36-02063602-generic take from ubuntu natty
/var/log/Xorg.0.log don't have error concerning
I don't habe /etc/X11/xorg.conf but I tried some tips on http://intellinuxgraphics.org/dualhead.html for force
frequency but xorg ignore it.
External monitor is old nec v72

Can it fix this problem? It is very bad for my eyes :-)
Thanks and excuse me for bad english