The main problem here is that you're not setting up in such a way that facilitates a vertical bar path over the mid-foot, and setting your back against the weight of the bar before pulling. I refer you, Jackie, to the famous and highly useful "Pulls from the floor" post:
http://startingstrength.com/resource...ad.php?t=38978 Read that, including the link to Rip's 2010 post, and implement that in your deadlifts.
If you can, find a gym where you can use round plates as opposed to the pseudo round ones with the three flat areas on them that your gym currently has. They don't roll, and the weight tends to settle on the flat parts, making the bar a bit lower to the ground and also uneven.