HELP! iMac G5 hangs at blue screen, but boots in Safe Mode

Please can anyone guide me to recover my iMac G5 PowerMac 8,2 running OS X 10.4.11.

Problem; Mac hangs on start-up at blue screen after grey Apple screen. Mouse pointer eventually appears but that is all.

Actions taken so far without success:

1. Disconnected the printer and rebooted - no success.

2. Booted in Safe Mode - first time the screen was completely scrambled but with safe mode log on screen showing through.

2.1 Rebooted in Safe Mode OK This has not occurred again and I have entered Safe Mode twice more without problems. But worrying!

2.2 In Safe Mode I ran disk Utility and verified and repaired Permissions, mostly old EpsonPrinter files.

2.3 I also verified the Disk, which was reported OK.

2.4 I was able to save critical documents to USB............ Phew!

2.5 Reboot in Normal Mode - no success

3. Reset PRAM

3.1 Reboot in Normal Mode - no success

4. Reboot in Safe mode - works fine. NOTE: time and date appear to be correct and dont need resetting.

4.1 Run Disk Utility again and Verify Permissions - OK. Nothing needed fixing.

4.2 Run Disk Verify - Passed OK

4.3 Reboot in Normal Mode - no success. Hangs at blue screen with mouse pointer visible and working. Then pointer vanishes.

I would be most grateful for your help in moving this forward