I was running 0S 10.4 on my Powerbook Titanium. Have just installed 0S 10.4.8 update via Apple>Software Update. Everything installed fine until re-boot, now the machine stalls after i get passed the username password bit... the desktop starts to load but i only half an inch of the finder menu bar (the bit top right with the 'spotlight' icon) displays and nothing else... a blank desktop image!

Any ideas? Please help!