Start up problems - Powerbook 12" G4

I run a 2003 Powerbook G4 12" 867 MHz.

I use Leopard - OS 10.4, and always use software update to get the latest updates. I can't remember exactly, but it will be 10.4.12 or whichever is the latest.

I recently updated with a security update - it came up with an exclamation mark, saying that an error had occured with the update. It asked me to restart, and now will not load to the 'log-in' screen.

It starts , loads the grey screen with apple logo, but then just settles on a blank blue screen, with a spinning disc. I don't have the original OS X discs, so the only way I can do anything is to start in 'Single User Mode' by holding down Apple and S at the start tone.

I've tried the 'fcsk' disk utility, which said that no errors had been found. Still, everything I've tried has still just led to a blue screen, and failure to load the log-in page.

Expert suggests would be much appreciated. Thanks, Olly

Get your hands on the Tiger OS X.4 or Leopard OS X.5, you seem vague as to which you are running, full retail install DVD somehow, even buy it, and boot from there and run Repair Disk.

The install DVD is an absolute vital piece of equipment and you must have it as you have found out alas.