If you have another Mac do this: put the files that you can't delete into another folder and remember where that folder is.
connect the two computers via a firewire cable. Start up the "problem Mac" in firewire mode. It will show up as a disk drive on the desktop of the second computer. Navigate to the folder with the troublesome files and trash them. Select the "problem Mac" from computer b, eject it, disconnect the cable from both machines and restart the "problem mac." This is a simplified explanation. If you need more detail let me know and I will provide it. Another possibility.
