TweetYou either have week ankle flexors (the muscles on your shins), poor shoe cushion or a crappy treadmill. Sorry to be so blunt.
Solutions:
Shins: sit in a chair with your feet flat on the floor in front of you. Practice flexing your ankle joint (raising your toes towards your knees). Do this for as long as you can, 30 seconds, 60 seconds, whatever. Wait a minute or two and do it again. Do this every other day for two weeks then just once a week.
Shoes: find good shoes that fit your feet properly. If you have high arches, get New Balance or Mizuno. If you have moderate to low arches then most shoes should work. Nike is one of the worst shoes for arch support. Just feel inside one and see for yourself. If you are not in a position to get new shoes then go get arch support inserts. Good realiable ones will cost about $25 to $35. If you need more cushion then go by inserts, but get the good ones. Again, they'll be about $25.
Treadmill: If you do the above two things then you should be able to handle a crummy treadmill. As far as treadmills go, I like Precor and Startrac personally because the shock absorbers are pretty good. I'm sure many others have them now but those are the only two I can recommend from personal experience. If it's at your gym and you have to deal with what they give you, then I recommend you run outside. You can burn more calories making your body move than you can running on a moving belt. Period. And, it's not as boring.
Good luck bro!