Cannot boot computer past apple logo, text is displayed saying aDebugger called ?

Hello

I have been having issues booting up an iMac computer, it doesn't get past the apple logo before prodcuing text and a greyed out screen that refers to 'Panics', 'double Panics', kernal traps, deBuggers?

Not sure where to even begin really.

It does the same when I try to boot in safe mode.

Any ideas, can some one show me where to begin?

cheers

Matthew Trott