It’s a movie probably from the 80’s or maybe 90’s, it’s about a strange, teenager who likes rock music and uses the computer, he uses some strange tapes into the computer. At some point in the movie seems like he is inside a memory or something or he is dreaming about killing the girl he likes in a party. There is a scene where a old rocker men with big fingernails show up in his room.
Brainscan (1994)?
http://www.imdb.com/title/tt0109327/?ref_=nv_sr_1
Trick Or Treat perhaps? (Not so much the computer part, but the rocker with long fingernails in his room part fits…) http://www.imdb.com/title/tt0092112/