Fatal CRC error on Dungeon Siege 2

Have the Deluxe edition w/Broken World expansion.
Installed correctly, Vista SP 1, 4gb ram, 256mb video.
Confirmed no updates to system out there (Direct X, BIOS and video settings).
Have started getting fatal CRC errors at same point in 1 game while looking
for picture / graphic of something in the game (have screen shots of error
I deleted and resinstalled software from scratch.
Started new character.
Still getting fatal CRC error msg w/different .
Any ideas?
Are discs defective, should I ask for a replacement?