Delete the songs from your iTunes library and redownload them by clicking "Purchased", under Quick Links at the top right of the iTunes store.
If this doesn't work contact iTunes support here:
Thanks for your suggestion. I did that, but there was no success. Unfortunately, the tracks still are not fully downloaded, and it is now downright frustrating. It has totally stopped me from making any further purchases of music from iTunes. When it comes to music, I think I will just buy from Amazon or something.
This is ridiculous. I have made a report to Apple, and only if they respond with a workable solution will I begin to buy from them. I will simply have to wait until they respond.