kernel_task is using 90% CPU, what could be the cause? I have a 13" MBP late 2009, 2.53 GHz, 4 GB RAM, and on OS X 10.8.3. As soon as I boot up the fans start going at the highest rpm and like I mentioned the kernel_task is always at around 90% when no apps are being run. I read somewhere that I should try safe boot and see the effect but there is none.
Any ideas as to what is causing it?

Thanks
It might actually be spotlight trying to index your drive.