My new Toshiba Satellite 2410-404 has the same problem, and on linux-laptop.net I saw similar problem reports with latest Toshiba series. It is always the same story: you can work on the console without any flaw, and you can work with X with "XkbDisable". This is, of course, exteremely uncomfortable and requires manual hacking on a large xmodmap scheme to simulate the local keymap normaly provided by Xkb. Working with Xkb keymaps causes a duplicated char after every 3-10 keypresses.
Branden, please provide this to someone who may know what is happening here. If you or them need any help, tell me what to do on helping debuging. Gruss/Regards, Eduard.