Dreamcast Guides : Browser Flash Memory Reset

- Turn the Dreamcast off
- Put the controller in port B
- Turn the Dreamcast back on
- When you see the white screen that says "SEGA" in big, blue letters, hold down X and B on the controller (it's the screen right after the Dreamcast screen with the red swirl)
- Hold down the buttons all the way through the Planet Web screen
- Upon reaching the next screen, the memory is reset
If you have the browser that comes with the Dreamcast Magazine:

- Turn the Dreamcast off
- Put the controller in port B
- Turn the Dreamcast back on
- After selection "Web Browser 2.0" from the menu, you should see a screen with the Dreamcast controller
- Hit A to advance, then immediately release A and hold down X and B on the controller
- Hold down the buttons all the way through the Planet Web screen
- Upon reaching the next screen, the memory is reset

From sega.com: