Comment 9 for bug 355057

Gosh, I think I found the little bugger. It seems this has been that way near forever but probably did not always matter (as long as your font only has 256 characters). The problem lies in the function that returns the font data of a vga console. It will only write back the first 256 characters but claims the returned font has 512 (as it had). So after every switch of the console there is the chance of corruption.
Some of my systems seemed to have initially 256 character fonts, so your example text and also those special characters on my keyboard where fine. Just after loading a font with 512 characters in it you will immediately see the corruption.
The attached patch fixed the problem for me. I will also upload some Jaunty based kernels with that fix, so you could test with them. Should this work for you as well, would it be ok to add you with your email as a "Tested-by"?

The kernels are at http://people.ubuntu.com/~smb/bug355057