Sounds like you got a corrupted dump, use NUS downloader to download the system update for the same version of system menu that your Wii has. Then install it using the wad manager.
Before installing be sure to remove things such as bootmii, preloader or anything that alters the system menu from normal functionality excluding the homebrew channel.
The proceed to redump your system menu, I recommend Wanikoko's file system dumper to achieve this.