Character movement bug?

My question isn't difficult, but it seems there's no easy way to fix it, looking at this guy's problem: http://game-editor.com/forum/viewtopic. ... +animation
I have the same problem, but only for moving left, right, and jumping. When I use the regular key down events built into GE to make my character (Mario) walk and jump, they mess up when they are pressed quickly in certain sequences. For example, when I press right, then press left quickly, Mario will switch to his standing postion, but continue to move left. (the same things happen in the caveman demos, which is where I learned how to do simple movements). I think this has something to do with the Key Up events I made, but I don't see any other way to fix these animation problems. The code in the topic above is very complicated, and I don't understand it well. Is there a simple way to fix these little bugs, or am I just going to have to deal with them?
I have the same problem, but only for moving left, right, and jumping. When I use the regular key down events built into GE to make my character (Mario) walk and jump, they mess up when they are pressed quickly in certain sequences. For example, when I press right, then press left quickly, Mario will switch to his standing postion, but continue to move left. (the same things happen in the caveman demos, which is where I learned how to do simple movements). I think this has something to do with the Key Up events I made, but I don't see any other way to fix these animation problems. The code in the topic above is very complicated, and I don't understand it well. Is there a simple way to fix these little bugs, or am I just going to have to deal with them?