I had problems registering my first two years and I came in with almost 60 credits (that was before registration was by class - it was by credits). By 3rd and 4th year I had no problems (other than an administrative problem my 5th year) since registration was by class then credits and I had a lot of credits at that time. The class that gave me trouble, the prof actually registered all of the 4th years manually who needed the class for graduation, it was really nice of him, we were way over capacity and he wasn’t paid more or given an extra TA.