Several people have reported that some of the CD key characters didn't get printed at all or were smudged in the printing process.
Some people are reporting that Codemasters is now willing to give you a valid CD key over the phone if you've got a CD key printing error. Just have your original OFP CD on hand, as they'll ask you about some unique information printed on your CD. Here's CM's worldwide contact page.
If for some reason, CM refuses to deal with you over the phone, your alternative is to either contact your attorneys or repackage everything and exchange your copy of OFP for a new one at the place of purchase. If you ordered it by mail, make sure you follow the seller's return/exchange instructions and include a note describing the problem.