I've just recieved an iMac from my mother. Everything was going great until I decided to change the name next to the "house" icon in the finder sidebar to my own. There are now two users, I can't find things, things are disappearing. She had spent months cataloguing movies in iDive, and after several tense moments I discovered they were still on the computor, but not in that program. How do I fix this? I'm so confused, my ears are ringing, and I'm afraid of doing irreversible damage. please, someone help me!