Asus Express Gate ("EG") is a "mini" Linux environment that boots fast and offers limited subset of functionality such as Web, Skype, IM, some broser games etc. (3-5 secs in fast system)
If you have configured your mobo to "non-IDE" mode (e.g. using mobo-RAID), the EG will not recognize your config and thus will not work. -pity, but don't ask me...-
You can disable the EG from BIOS or you can unistall it, but be aware, some models require a CMOS reset if you just uninstall the EG without disabling it from BIOS.