Dreamcast System Cheats
Dreamcast | Submitted by GamesRadarReset Games from Controller
First hold L + R + A + B + X + Y then press Start to reset the system on most games
Dreamcast | Submitted by GamesRadarDelete Internal Memory
Before turning on the system press and hold X + B on controller B. Turn on the system and release the buttons after the time/date appears. This will reset Date, time and Network settings
Updated: You have to insert the Web browser disc, then hold X + B on controller port b. You have to use the Web Browser disc that came packaged with your Dreamcast. Also don't forget to remove the VMU or else you will lose anything you saved from the internet.