this has nothing to do with the 4th core brother, this is def a driver issue.

he needs to do a full reinstal of OS and then look at getting updated drivers for all his bits, i suspect the sound driver is the issue.

i would instal everything, and leave the sound driver to last, and give it a try without that driver.

then instal sound driver, to see......... my spidey senses are tingling with this one

edit: yes if you enable the 4th core it appears ehhh? again i suspect windows just doesnt like it, did you instal the OS with the 4th core enabled, or just enable the 4th core on a 3 core instal?