[X4U] help, iMac G5 will not boot

[Kansas Territory]

Have a 17 inch iMac G5.     Running OSX 10.4
Try to boot it up.. I get the gray Apple and the Spinning wheel.  But  
nothing happens beyond that.

I booted up into Single user mode.  Ran the fsck  that reported back  
an error of some kind, said it was fixing it.. etc.

I ran fsck again. this time it reported NO errors and that the drive  
was fine.

Still when I try to boot up this computer, Gray Apple, spinning wheel.

Any suggestions  ?

Kansast