Had the same for for another file.
What i did was to make sure the files were still in the same sprocket download folder.
For me: "C:\Users\"username"\My Documents\Sprocket\"
Deleted the small md5 files but left the others alone. (Also made a backup of all the files, just in case).
Then starting the sprocket download manager, it would check the files to see if they are alright.
For me it would download a few bytes of one of the files, as if it wasn't completely downloaded. And that was it.
Installing it this time directly from that folder, and problem was gone.