successfull debin 6 install, but messy screen after bootstrap
 

after sucessful installation on my laptop, grub worked properly, and then linux bootstrap started, just after some text, the screen goes messy. like old time TV with very weak signal.

computer model: dell e6410,
cpu: i7 620
graphic: 1440x900 screen with nvs3100 graphic card
debian version 6.0.6 i386 and amd64(the same problem)

on the messy screen if i switch virtual terminal it's definitly changing, the alt+f7 one is colorful full screen mess, others are black and white part screen messes. on the text terminal I type root and password it obviously logged in, and i can't see what's going on but commands going properly like, if i type poweroff [enter] will power off the machine.


this is installation media i downloaded from
http://ftp.nl.debian.org/debian/dist...ages/hd-media/

this is installation instructions from debian
http://www.debian.org/releases/stabl...-copy-flexible

i've tried i386 and amd64 versions both acts the same.

before this i successfully installed ubuntu 10, 11, 12 with everything allright except just something mouse go laggy for every 10 second. after installed ubuntu 12, the mac style gui and no gnome classic by default, compeletely dissapointed me, and i decided to switch to debian.

so how can i fix this ?

I've just tried with a DVD media, the same problem, the installation guide was no problem with basic graphic mode, mouse and all windows look as usual.
but reboot after finished installation the same problem as previous.