my screen is freezing up and my programs stop responding

Okay ive done the disk clean-up thing, and cleaned out all i could… But i still only have 4.88g available. My computer holds about 38g. How do i remove some of the other 38g?

All of the diagnostic software on my computer completely ignores the mic portion, which is plugged in through a separate cord. The cord is in prime condition and the headphone part works perfectly.
BTW, I’m using Windows XP on a Dell PC.
Well I tried it on another computer and it didn’t work. Do microphones usually just die like this of their own accord?

I did a system repair operation in response to an error which made my computer unable to log into windows. I’m not sure if its my computer which is screwed-up in the first place or if its my own mistake; the system repair ended up deleting my program files registry and settings. Is there a way to restore all these stuff? ( Note: I did not do any sort of backup myself and my OS is Windows XP Service Pack 2.) Thanks.