A friend asked me to look at an ibook that was given to him. I'm a PC guy and am not particularly familar with macs -- especially with troubleshooting them. The machine sometimes boots to the login screen, but will freeze within a minute or two. The cursor cannot be moved, and typing on the keyboard will not result in any text on-screen. The caps-lock light does turn on/off, however. The machine does not always get to the login screen, and will sometimes freeze during loading of the OS and sometimes the system will display colored bars. I have removed the airport extreme card and tried different memory with the same results. I have removed the hard drive and sometimes the system shows a grey screen with a "folder" icon in the center, and other times will display the colored bars. I believe this is a hardware problem, most likely the logic board. Can anyone confirm or deny this. I have thought that heat may be an issue... The fan does not seem to cycle. Sometimes (not always) it will cycle for a second at boot... but not every time.... and never after that. The system does get quite warm, but I know they have a reputation for that. Assuming we can identify the faulty part(s) where do you recommend they be purchased from? Thank you in advance.