My machine had been running fine. It locked up on a reboot at the Windows logo, it will not boot from there. When you try to boot in safe mode, you get the blue screen of death with an error "BAD_POOL_CALLER". From everything I read this could be caused by numerous things. I have loaded no new software etc. It will not boot from the OS CD can't get to operating system at all. Time for a new hard drive? The machine is a Dell XPS 400 about 18 months old. I have worked on alot of errors, I have never seen this one. Any insight would be appreciated.