I have a big problem. My iMac G5 has seemingly crashed. I was googling around when I had a system error. I shut it down & now every time I try to start it up it begins it's normal OSX startup & then goes to a black screen & promps me to login. I can login under my username & it says "Welcome to Darwin" From there I have no idea what to do. I am not technically advanced enough to know any commands, I am lost. What to do? Any advice would be appreciated.