Comment 6 for bug 133662

This issue has been fixed but in another way. Sony_acpi is deprecated because of sony-laptop module which replaces sonypi. The acpi-scripts has been changed today to use the sony-laptop path which works but there are two problems.
Sonypi have to been blacklisted or removed otherwise brightness has one less mode (0) and two less (0 and 8) than the patched sony_acpi https://bugs.launchpad.net/ubuntu/+source/linux-ubuntu-modules-2.6.22/+bug/117327 for TX and maybe other Sony notebooks.
Without that, sonypi and sony-laptop have to be removed and only sony-laptop has to be loaded again.
Sony_acpi could be removed too if there is a solution for https://bugs.launchpad.net/ubuntu/+source/linux-ubuntu-modules-2.6.22/+bug/117327 but it doesn't hurt since it isn't loaded in Gutsy atm.