Why am I majoring in computer science

So I followed the teachers instructions to upload my movie and it doesn't work. I burned the movie using idvd and it doesn't work. The whole point of majoring in CIS is so that these things won't happen when I am more knowledgeable about the computer....But if the teacher doesn't know why it doesn't work...What are the chances I ever will? Am I just wasting my time...Cause I could major is something easy like communications! ;)