need help for xorg on laptop

["Morgan M.C.M-L" <morgan-informatique%laposte.net@localhost>]

Hello

I've finished an Acer Laptop installation but X gives me vertical lines 
of red and black. On this Acer aspire 1350, I've done this :

X -configure
vi /root/xorg.conf.new (to write in this):

HorizSync       31.5 - 48.0
VertRefresh     59.0 - 75.0
Modes 1024x768

X -config /root/xorg.conf.new gave me vertical red an black lines and 
freeze the lapptop.

Modifying [Driver "via" by "vesa"] gives me :
Vesa no matching modes
Screen found but bobe have a usable configuration

Any ideas ? Horiz and VertRefresh does match on slackware and 
backtrack... 

Thank you.