G4 eMac Desktop Disappearance !

Firstly apologies to Mods if thread placed in wrong area: don't know if problem is OS X or the hardware itself. Please move as you see fit.

Computer is a very, very lightly used g4 emac, 1.42ghz, 2 gb ram. HD has 25gb of free space from 79gb. OS X 10.4.11

Last week my personal desktop froze on a few occasions requiring hard shutdown/restart - never seen this before. Whilst it was working I verified and repaired disk and disk permissions just be to be safe. Passed.

Turned on the following day to have no desktop; just a light blue screen with a movable cursor. No menu. Nothing to select. No 'BONGS', No unusual HD sounds, no rattling or complaining - just pale blue screen.

Shut down and restarted in 'safe' mode' - all is fine; eMac works fine albeit with the normal 'safe' mode limitations:

Q. where has my desktop gone, how do I access it again, will what's happened to my personal desktop also happen to 'safe' mode ?

Much reading later......things I have done:

Start up from OS X Tiger DVD> Disk Utilities> repair and verify both disk and permissions again> some fixes required and effected> PASSED.

Still can't boot to personal desktop.

Acquired use of external HD and Macbook Pro core i7 with intention of putting Tiger OS X on external drive to boot test eMac and perhaps clone off existing eMac material before wipe and fresh OS install.
Have erased and partitioned Touro EHD on both eMac and Macbook Pro, setting as 1 Partition and Apple Partition Map then using OS X DVD tried to load on to Touro. Won't do it - puts up error message saying OS X is 4.7gb and there's not enough free space on selected external drive. There's 499gb free !

I don't know how much longer eMac will last and I no longer know what to do for the best - I'm a week older and no further on........

Any help would be massively appreciated. Thankyou.

macludite