i have installed slack9, recompiled the kernel, and when I boot it up with vga=771 (it works with the old kernel) I see only black-screen. I have included the svga support into kernel

I think you will need to examine what changes you have made to your kernel that could have a bearing on the display. Are the relevant modules compiled for your video card?

You might like to give a few more details about your hardware.

some alternative options from my lilo.conf:
# VESA framebuffer console @ 1024x768x64k
# vga=791
# VESA framebuffer console @ 1024x768x32k
# vga=790
# VESA framebuffer console @ 1024x768x256
# vga=773
# VESA framebuffer console @ 800x600x64k
vga=788
# VESA framebuffer console @ 800x600x32k
# vga=787
# VESA framebuffer console @ 800x600x256
# vga=771
# VESA framebuffer console @ 640x480x64k
# vga=785
# VESA framebuffer console @ 640x480x32k
# vga=784
# VESA framebuffer console @ 640x480x256
# vga=769

I have GeForce 4MX card.
The problem is that I don`t know what was included in the original generic kernel. Is there any way I can find this out?

I just went through this myself...first off, you need to recompile your Nvidia driver if you haven't already (you probably got/will get a "screens not found" error out of XFree86 if you don't).

Second, you may very well have removed VESA Frame buffer support, which is what allows the VGA modes from the console. VGA=771 requires that to display. If you can edit your lilo.conf, change the uncommented VGA line to VGA=6 and reboot, see if you get a console. You should get something....let us know how it goes.

thx a lot I`ll try that and let u know