process explorer from system internals will tell you which process is using all that CPU power. http://www.sysinternals.com/

If it is nero express, then is there an option to do a custom install and install they very min of what you need... and see if that helps?

 

Some software may not be compatible with your operating system. I have seen problems similar to this caused by CDRW software when a computer would always reboot after you shut down. You might look for a newer version of that program from the maker of the software on-line.