Back in the good old days, graphics were graphics and text was text. These days even something that looks like a text mode might be using the framebuffer and technically have a graphics resolution.

We encountered this problem recently when recommissioning a server.  To enable remote access should the server encounter a problem many of our servers have a KVM over IP daughterboard which allows console access if all else fails. This particular device also allows a remote user to hook up a local CD ROM or ISO image to allow a remote install to take place.

This was what we attempted recently with Ubuntu 10.4 (LTS). Unfortunately the graphics controller on the KVM daughterboard (in this case a Supermicro M3296) operated fine until the installer booted but then showed a corrupt display claiming to be 648x481 pixels in size. 

So, instead, on one of our datacentre visits, we reinstalled it in the conventional way, however afterwards the screen was still corrupt when viewing using KVM over IP.

The reason for corruption is because of a particular mode used by the linux console. This can be edited in the file

/etc/modprobe.d/blacklist-framebuffer.conf

and inserting

blacklist vga16fb

solves the problem.

I also believe that the kernel options 

vga=normal nomodeset 

should have the same effect during install, but we haven't tested that theory yet.