The version of module-init-tools you are running currently has this bug
fixed, but you might still have the old broken version on the initrd
which is generated at installation of the kernel-image package.
Could you try to regenerate initrd either by running
mkinitrd -o /boot/initrd.img-2.6.6-2-686 /lib/modules/2.6.6-2-686
or by uninstaling and re-installing kernel-image-2.6.6-2-686 and check
whether the error is fixed? (I am not completely sure about the
initrd-commandline, so if it does not work please try the purge+install
approach).