Hello. My laptop had been having several problems in the past including graphical and audio issues. The graphical issues were pegged down to me using fixed mode for my switchable graphics, and the audio issue ended up being the result of an overheated motherboard, which was replaced along with the cooling unit when the fan started to buzz. I sent it in to the repair shop just before winter break, so I got it back mid December. On February 3rd, and again last night my computer locked up. The first time it did so I don't recall there being any change in the sound, but last night the audio was stuck in a stutter as well. Nothing could get a response out of the machine. However, I could hard-shutoff the laptop by holding down the power button.
Event Viewer has nothing. I think it may either be a cooling issue with the new fan or the new motherboard having different drivers
EDIT: Also I don't know if this would be relevant but I checked after the second freeze-up and Defraggler reported my HD at 25% (way more than the default defrag said) so I let it defrag overnight.