This is probably more appropriate for the G6 subforum, and you should probably post more information... (Are you receiving the error directly after booting the game? Are other games working fine?)
A few suggestions:
- Ensure that you have a good, verified ROM (CRC matches)
- Ensure that you are using the latest U-Disk Manager (4.6D)
- Transfer the ROM using SafeMode (No Soft-Reset) in the U-Disk Manager (Try w/ No Trim)