PC doesn't stop running evenafter shutdown

[Mkrrish]

My PC [core i3 540 3.07GHz, Transcend 4GB(2x2GB) RAM, Intel DH55TC Motherboard(stock cooler), Zotac NVIDIA 8400GS (1GB) Gfx.] doesn't stop running even after shutdown is initiated. But i see "Shutting Down" command and the monitor goes to OFF mode. Even the PC light turns off.
The IC fans and the cooling fans keeps running.

 

[smorizio]

turn the power supply off. pull power from the wall and clear the cmos..the mb bios is stuck in reset mode.