When downloading something from the playstation store, under certain conditions the data will seem to have downloaded correctly, however when you try and install the file it will progress so far and then say the data is corrupted and the install will fail.
There is a theory on the Internet that if you download the file again without selecting download in the background this cures the problem, unfortunately this is a myth. The problem can occur wether background downloading is selected or not.
The problem is actually caused by interference from knotted cabling and transformers for other electrical appliances. All you need to do for a successful download is make sure you have a good Internet connection..preferably wired and make sure the PS3 is away from any transformers, power adaptors or bundles of cables. Delete the corrupted download, download it again and everything will install correctly.