G4 problems, dunno whats going on....

Hello everyone, I have an iBook G4 that has recently stopped booting up. A week or so ago it froze up like the computer was thinking or processing, but never got back to functioning normally so I was forced to turn it off. Now every time I start it up I get the zipping sound, the starting chime, then it goes to the gray screen with the apple logo with spinning thing below it for a while, then eventually turns off and goes black screen (It never gets to the password entry screen). I have a feeling that it is the OS software, however I bought the computer used so I do not have the OS CD. Should this be fixed by rebooting the OS CD or do you think this is a more complex, expensive problem?? Thanks for your help!

It should be fixed by reinstalling the os.

obtain a restore CD and boot off of it. Then use disk utility to scan your hard drive for errors. It may be you just need to reformat, or it could be the sign of a dying hard drive.

Thanks for the help guys, will try....