PC restarts automatically

hi techies,

today i found my pc is very slow, so i uninstall the trend-micro antivirus and install the nod32 smart security, after that when i tried to update, update doesnt start, so i restarted. after that PC is automatically restarting again and again. i tried all boot options (safe mode, last known good configuration and disable automatic restart).
kindly help me.

thanks
sim