This appears to be a disc read error that commonly occurs with disc based game media.
Check the disc for scratchs and smudges. Give it a good cleaning and try again.
Some game shops offer disc rebuffering and I'd suggest giving that a try if all else fails.
Another problem could be the laser in the Dreamcast wearing out, however this problem would occur in other games and can be rare if the machine is taken care of.
Give the game a good cleaning, sometimes simply water and a soft computer screen cloth can be used to clean these discs enough.
Answers & Comments
This appears to be a disc read error that commonly occurs with disc based game media.
Check the disc for scratchs and smudges.
Give it a good cleaning and try again.
Some game shops offer disc rebuffering and I'd suggest giving that a try if all else fails.
Another problem could be the laser in the Dreamcast wearing out, however this problem would occur in other games and can be rare if the machine is taken care of.
Give the game a good cleaning, sometimes simply water and a soft computer screen cloth can be used to clean these discs enough.