Recurring hard drive problems in MacBook Pro.

Question

Hi all,
This will be a fairly long post, so I apologize beforehand. I feel as though I should share as much information as possible in order to try to nail down this problem as best as I can. So, here we go...
About 6 years ago I purchased a 15" MacBook Pro. I had been using it just about nonstop for about 5 years, only closing the lid when I transport it, even in 3 hour car rides, and had no problems. I was using snow leopard for the duration of those 5 years. In August of 2012 I decided to take a year of study in Denmark so I could spend time in Europe. I wanted to make sure I was set for the year, so when mountain lion released, I purchased it and upgraded from snow leopard to mountain lion while skipping lion altogether. I also purchased a charger consistent with European outlets and power supply upon arrival. I used the computer just fine between the time I upgraded in early August until about the middle of October when the dreaded grey startup screen appeared with the folder and the flashing "?". I took the computer to the premium, certified Apple reseller in Copenhagen to have them look at it. i ended up paying to have the hard drive replaced because I was out of my warranty period. They fixed the computer and everything seemed to work fine.
Two weeks later the hard drive failed again. I brought it to the guys at the service desk again and they said "Yeah, it's the hard drive. We'll replace it for free since you were just here 2 weeks ago." So I let them fix it. When I received it a couple of days later I brought it home to restore everything from my backup and during the restoration process the dang hard drive failed again. At this point I had some friends coming to visit me so I got the computer repaired, didn't use it, and sent it home with them. Then, my parents went out and bought a newer 13" MacBook Pro and sent it to me.
This computer was wonderful. It worked great...for a month. Then the battery went out. Still under warranty, the computer hospital patched my little guy up and I was able to use the machine again. However, two weeks later, guess what happened? You got it! Another hard drive failure. At this point I was like "Ok, this has to be a user error." So I did some digging on the Internet and found that just closing the lid and hauling it around is not the way to handle the computer. So I started being more conscious about it, not running for trains, etc. I got the computer repaired again, this time under warranty and everything was great for another month when the hard drive failed again.
When I took it to get repaired again I asked what the heck was happening, why the same problem had been affecting two separate machines. They essentially told me to make sure the machine was powered all the way down. That makes sense considering what I had read previously. So this time I took all the necessary precautions and turned it off before I moved it anywhere. This method worked fine for two weeks. Today the hard drive has failed again.
The weird part about this story is that my dad has been using the old machine I sent with my friends ever since the end of December and has had zero problems with it, meanwhile I'm still having hard drive failure after hard drive failure. I just don't understand what's going on. Is this a user error? Am I doing something blatantly wrong with my machine that would cause this problem? Is it the fact that I've upgraded to the mountain lion OS? Is it merely the fact that I'm in Europe trying to use American products, even though I've gone out and bought the proper charger for the part of the world I am in? It's starting to become a huge annoyance, especially considering my finals are all next week and I have papers/presentations to prepare. Other than the obvious remedy of getting another repair job, is there anything I can do differently to make sure this doesn't happen again? I find it hard to believe that this is a fluke with 7 or so problems in two completely separate machines...
Sorry for such a long post. I figured that in order to get help people would need to hear the whole story. It's kind of unique and there are a lot of factors at play here. Any help is greatly appreciated!
Thank you for your help and your time!

Answer 1

Well that's a tricky thing - I guess I should have said that it wasn't a completely new charger that I bought. The Apple certified store had just the wall outlet portion available. You know where you unplug it from the box and you can either make it a short plug or a long one? They gave me the long portion for the European outlets. The model number on the box on the charger from the old portion of the charger is - A1344. It's a 60W MagSafe power adapter. The guy at the store told me the box automatically converts so there's no need for a converter, you just need to plug it in. Can't find anything denoting a model number the half of the European charger. Both are Apple provided - the old portion is from my old computer of 6 years ago that is working at my dad's house and the newer half from Europe was from this Apple certified store. Hope that helps you out. I just want to make sure I don't make the same mistakes if they are my fault once I get back home. The Apple store is a 2.5 hour drive from me as opposed to a 15 minute train ride.