I think that obsession means it is preventing you from doing what you would normally do. There is a time and a place for everything...if you are only on PC and ignoring work, school, chores, or whatever..in my mind it's a problem...if it is benefiting you and not interfering with your daily life then I think it's okay.

My reading/posting on PC goes up and down depending on my emotional state. Sometimes it has been a lifeline for me.