iBook G4 - Major Crash

I've got two problems...

1.Started up my iBook G4 (Mac OS 10.4) last night and I got this message...

init: can't exec /bin/sh for single user: no such file or directory

Click to expand...

It was working fine two days ago when I last used it. Don't know what is causing this as I hadn't installed any new software etc.

2. Thought I could re-install the OS but after inserting the disc I've no way of ejecting it.

Haven't a lot of experience using Macs so all help greatly appreciated.

[EDIT]
actually think the OS is 10.3.9 if it makes a difference.

Rob