Interestingly I have an X553m with the same problem, or at least I did up until about 5 minutes ago...
One thing I've heard over and is that the keyboard is too flimsy and causes problems hitting the keys, this certainly seemed to be the case because I was having issues with the uijk set of keys in particular, which is about as far from the outside edges as you can get.
Now I'm not necessarily recommending this as it is a bit of a hack, however I have found that by placing a piece of cardboard inside the laptop (after making sure it is non-conductive, etc.) around the center of the keyboard on top of the rubber supports (which are no where near enough to support the keyboard on their own), and then closing the keyboard / top of the laptop back on top of it, I have had no issues since.
I may need to look into securing it properly, and possibly coating it in some sort of latex, or even electricians tape to keep it away from the motherboard, just in case there is a chance of conductivity, but it seems to have corrected the problem.