Haha, that's why I always run on the treadmills at the very back of the room...the scenery is great!!
As far as form goes...I just wrote a long paragraph about it and then did a search and found this good article
that breaks things down pretty well.
Cross trainers don't give you the support that you need for running. They have a lot of support on the sides for lateral movement, which is something you don't need for running. They often have a very wide sole. I replaced my shoes every six months when I ran, but they needed it about every four months. I was putting down a lot of miles though. If it continues and you think it might be because of the shoes, then try putting some new insoles in. That can help a good bit and it's cheaper than buying new kicks.