CRC is Cycleric Redundancy Check. It happens when a file is incorrectly copied from one place to another (incomplete or damaged file). It could be a problem on amazon's end, I am not sure.. but to be safe, I would try to unzip the file with Windows Explorer, since the built-in unzipping utility does a better job at unzipping stuff. If you are noticing a CRC check when you execute installers or programs on your pc, I would look into anti-virus, or maybe invest in a new hard drive since bad clusters may be to blame. Bad clusters seem to spread like cancer.
Edited, Oct 6th 2012 7:10am by mokatu