I had this problem, I downloaded the latest drivers for my motherboard and installed them. But because you've recorded sound before, try this:
Go to windows volume control(double click the little speaker icon in the bottom right of taskbar) "options" > "properties" then "adjust volume for".. select recording, make sure that stereo mix is selected and it is not set to low volume
I put all them back in, and it's still not back, maybe its a bug then!
OK I got it, "logos2.dds" was the problem, there was an advert missing on it causing this pink void, so just put the backed up one back, and it should be fine
Well I've been changing textures around lately, and I seemed to have boobed up my SO, screenie attached, so if someone could tell me the right one to put back in my dds folder