If an error mentioning: CRC, cyclic redundancy check, data2.cab, data3.cab occurs during the installation of a disk copy of the game:
- Make sure that the CDs are not dirty or scratched – damage may impair the correct reading of the CD
- Try installing the game from the hard drive. To do that, create two new folders on your system, one for disk 1 and one for disk 2, and copy into them (using Copy-Paste) all the contents of the two The Witcher 2 CDs. If during the copying process no errors occur, open the file Setup.exe which can be found in the folder with the contents of the DVD1 disc. When you are asked to insert the second CD, press the Browse key and afterwards select the folder into which the DVD2 was copied.
- Alternatively, just claim your digital backup copy of the game from www.gog.com/witcherbackup More info on redeeming the backup copy can be found in this FAQ entry.