Desktop Icons Flash Off & On Then Goes Back To Log On

Powerbook (OSX Tiger) turns on, with no chime, then goes to log on. I log on successfully, then desktop with icons appear flashing off and on, along with my dock. At this point: I have to be very quick to attempt to open anything like Finder, before the message pops up saying " Your computers time & date are not set correctly...before March 24 2001, and then goes back to log on. If within 2 seconds I open for example: itunes, I see all files intact. Then I get a message: Itunes has unexpectedly quit.. then things again go back to log on. I do not have time between the flashing intervals to open Apple menu, Terminal.app or much else to fix the problem. I have no acess to another mac with a firewire, not that I have any experience with that. About 2 years ago I had changed my optical superdrive with no problems. 1 year ago I had replaced my pram battery and all worked fine. The problem seems to have happened after downloading mpegs online. I would like to keep all of my jpgs, mpegs & mp3s if possible. My factory Install/Restore disc will not go farther than 'Select Language'. Hardware test is ok and goes to log on. I wish I could open Terminal.app on start up, like a DOS screen, but don't know if thats possible. Any suggestions?