This can happen if you cancel a render, especally if you cancel it while Anim8or is rendering the first frame of an AVI. If Anim8or does not show up as running in the Applications tab of Task Manager, but the Anim8or process is running in Processes, I would kill the process (highlight it and click End Process). If anything other than System Idle Process is keeping the processor busy after this, like Explorer for example, the best thing to do is wait it out. Once the CPU is idle, reboot. If it happens again, take note of precisely what you were doing when it occured, how you shut down Anim8or, if you were rendering or not, etc.