Hi I am facing this problem too. I have a '11 macbook pro 13" and replaced HDD at first (having two of them I did it effortless and moneyless), then without any fix decided to buy another HDD cable and problem seemed to be fixed. I faced the same issue again, still after the same amount of time (avg 3 weeks) so the flat cable failed again. I am currently at the second cable bought and decided to not go for any buy again by now.