Cannot boot iMac G5 - help please!!!

[isolated]

Hello everyone,
Thank you for your time... I am having the startup problem i am having... my mac loads thru grey screen and stops at blue... flickering quickly and randomly to a black screen with "getty: (username)/dev/console device not supported.."
I have try'd to boot up in safe-mode which does the same thying and overdrives the fan. I reset the PRAM and PMU... all to no avail.
I had some issues last night prior to this... I could not gain access to SYS.PREF. options that i had previously locked. Within the account management pane i could not change my password succesfully and so on...
I dont know what the deal is... but i'm freaked out ><
Any advice greatly appreciated...
Thanks

note - I have also tried single user startup - "/sbin/fsck -fy" which said Hard Drive fine. then just the same cyclick BS
I have misplaced my startup disc, would i be likely to be able to boot from that - command C?

 

[H&Kie]

Do you have the Apple Hardware Test CD? If so, I'd recommend to do a test with it. As for your misplaced startup disc (I assume you mean an install DVD/CD) you can boot from it pressing only the "C" button while booting, immediatly after the startupsound has chimed. Same goes for the Hardware Test disk.

Hope this will help you