So I was going to comment on one of the other posts about the corrupted files but it was soooo long I decided to start a new one.
This should give me a hint that it is not HARDWARE....
To start with I am shooting a Canon 5d mkIII and RAW(.CR2) files
A slight kink in everyones generic answer that it is a hardware issue; I reproduced this on two computers using the same .cr2 files copied from the same original downloaded files. Lightroom corrupted files on import on both computers.
Also to test the answer it was corrupt before it went into Lightroom. I always copy the raw .cr2 file to my laptop and then to a external drive from the laptop directory, not from the compact flash. I looked at a .cr2 file with Photoshop and it was fine. Then I imported that same file with all of the other .cr2 files in the directory into Lightroom 4 and it was corrupt along with many others.
My disappointment is that when I tried to open the same .CR2 file, that was fine a moment earlier with Photoshop, it too was corrupted. I thought Lightroom was non-destructive to the original file.
I deleted that .cr2 file and restored the backed up file that was a copy of the original and imported that single file into Lightroom and it was now fine.
Sorry but not acceptable.