I was having the same problem too... I tried tweaking my xorg.conf (which is in /etc/X11 btw), but that didnt work for me. Nazmin, care to share your xorg.conf with us?
I changed my lilo to boot with standard vga, and removed hotplug from the bootup process and that fixed this. This was very wierd and i would love it if someone could explain this.
Anyhow, FWIW this is what I did... YMMV!
- Edit /etc/lilo.conf and remove all the lines that have "vga" in them... Then run 'lilo'. This tells lilo not to go to a fancy screen, i.e. the ones with more rows and cols during boot up.
- Run 'pkgtool' and there run the hotplug set up again and disable it. This prevents slack from searching for new devices at boot.
I have no idea why it worked. I have an intel810 and a Samsung Samtron 56V monitor. I have my xorg configured without any mention of my graphics card which is the onboard intel misery that shares my comps ram.
Btw, this is a pretty annoying a problem because as soon as I logout I used to get a blank screen which means just 1 login session per boot up. Luckily gnome had that login a new window, but it was still a pain.