The Witcher 2: Assassins of Kings -- in lieu of bracing for the impending hellfire, of course -- make sure you've got enough space on an NTFS-formatted hard drive to do it. Though the game's PC system requirements note you'll need "16GB of disc space," they don't mention you'll need that space to be on an NTFS drive.
One Joystiq reader found out the hard way, telling us, "My only hard drive with any storage space left on it is FAT32, and has resisted attempts to reformat. I discovered this hidden system requirement after buying The Witcher 2, downloading it, and attempting to install it this morning."
CD Projekt confirmed the situation to us this morning. Community manager Andrzej Kwiatkowski said, "Yes, we can confirm that The Witcher 2 on Windows systems only works on NTFS-formatted drives." Kwiatkowski further explained that the design is due to the limitations of the older FAT32 system. "FAT32 can't handle any file bigger than 4GB, and one of TW2's files has the size of 9GB."