Shift is pretty much an ideal jump key on the keyboard, and the solution to the problems that come up should just be to turn off StickyKeys and any other things that pressing Shift multiple times triggers. Either that or your computer has problems.
Anyway, I got this right before the ending screen (which I reached after clicking "Ignore"):

But all in all, for a game that has no enemies, this one is surprisingly fun to play. I think a lot of this is because of the unmixed NSMB graphics and the superb music choices.