Seems like a hardware probem as far as i can tell, with the info you give. Although you should be carefull when u replace parts, because it wouldnt be the first time that i have seen problems like this caused by a bad ide/sata/scsi cable.

Also, some motherboards have some kind of auto-overclocking feature. You might want to dig a little deeper in your bios settings.

Try to get a hold of pc-doctor on a bootable disc/usbstick and do the processor tests.

http://www.pc-doctor.com/products.php?language=english

 

open your box and listen to the hardrive while burning disks or playing the video game.

My guess is that its about to die on you...

Listen for a pop springy noise!