now when ever i go to backup time machine it takes 30 mins. to "prepare back up"(it didn't take this long even the first time i did it) and has not successfully backed up in 3 days. so is this a hardware or software issue, I ran disk utility first aid and it said nothing is wrong. i would prefer that i am backed up, because my computer live a pretty rough life, and all of my papers on it. thanks for the help.