Hi Nancy,
I'm new to this board, but your story sounds somewhat similar to my now 23 year old son. He was never officially diagnosed with Asbergers but we all pretty much think he has it, including himself. He suffered with depression in high school because he felt he never fit in. He also never studied for tests but always managed to do well. He scored extremely well on his college entrance exams, but totally failed his first semester of college. He went to a 4 year college right out of high school that was close to home. After he failed that first semester, we got him enrolled in the local community college so we weren't spending all that big money for a load of F's. I think he was still quite depressed and felt "why bother". Anyway, he also did poorly that 2nd semester at community college. Finally, he decided to take a couple summer courses and I'm not sure what happened in his head but he finally started to get the hang of college. He got A's in both classes and I'm happy to say that after that semester he has gotten all A's and B's. He's now a senior in college majoring in Computer Science.
I still worry about the job market for him, because he does lack social skills. He pretty lost touch with the few friends he had from high school after he left high school, and hasn't really made any new friends that I know of. He spends a lot of time online and I think he considers those people his friends. That's all well and fine, but he has no one to go to a movie with, or just hang out with. He just doesn't seem comfortable in those situations.
I still worry about him quite a bit. I guess that never goes away, but hopefully your son will adjust to college soon as well. It's tough being young when you have regular social skills and such, but when those things are hard for you it can be even harder.
Good luck and keep us posted.
People change and the best thing to do is to understand why they do and if it's making them better; if not, we do as our roles describe us in one's life. 
