[G4] Problems shutting down

[Hector I. Macedo]

Hi guys, I have a Quick Silver 800Mhz,

   Machine Name:    Power Mac G4
   Machine Model:    PowerMac3,5
   CPU Type:    PowerPC G4  (2.1)
   Number Of CPUs:    1
   CPU Speed:    800 MHz
   L2 Cache (per CPU):    256 KB
   Memory:    1 GB
   Bus Speed:    133 MHz
   Boot ROM Version:    4.3.3f2
   Serial Number:    RM211007MK3

PCI  scsi card
PCI  USB 2 card

OS 10.4.2  (it also has all the last updates in iLife and iWork)

the problem that has come latelly is that the compu refuses to be  
turned off or restarted by selecting it from the menu under the blue  
apple.
It starts the process and then it just stalls on the last blue  
screen, the little slotted wheel keeps spinning for ever. The only  
way I found is to physically press the front button for turning it  
off or the next to it for re-starting it.

Any help would be appreciated.










Hector I. Macedo