I'm not technically sophisticated but hope this helps.I had exactly the same keyboard problem as the OP running Debian testing (2.6.26-1-686) on an Acer Aspire 3503 laptop: the keyboard became unuseable in X but functioned normally in TTY1 etc.
/var/log/Xorg.0.log showed no errors.I resolved it by removing xkb-data 1.5-2, which the system then automatically "replaced" by installing xkb-data-legacy. The keyboard now functions normally.