Nintendo has tried to block homebrew during firmware updates in the past, often unsuccessfully. Now, as it rolls out version 4.3 of the Wii System Menu, stopping homebrew modifications once again seems to be its primary goal. From Nintendo's support site: "Because unauthorized channels or firmware may impair game play or the Wii console, updating to Wii Menu version 4.3 will check for and automatically remove such unauthorized files." Since it's hard to bill that as an upgrade, they vaguely add, "In addition, there are some behind the scenes enhancements that do not affect any prominently-used features or menus but will improve system performance."