Earlier today I was driving my Jeep and it was running just fine. I had to run to the local market a few hours later and when I got to 20mph it started making this high pitched squeal, which sounded like ti was coming from the front somewhere. It is fine when not moving and when I start it. I live in a few cold area during the winter (it is now 15 degrees outside). I don't know it that makes a difference but it seems awful strange that it was just fine a few hours ago and then all the sudden it starts with this noise. It was just sitting in the driveway the whole time. Amyone know what this may be?