Laptop Freezing Problem

I am using a sony vaio vgn-n110g from two years, without any issues as such. A month ago the laptop started hanging up randomly, without showing any error or any kind of disturbance on the screen..it would just freeze up. I discovered the fan wasn't working, and gave it to a local expert for repair. Diagnosing the problem , he replaced some ICs on the motherboard, and it worked perfectly well for 3 days after that.but again the same problem shows up now...it just hangs up without any marked pattern, but yes, if the hanging occurs when any music is running, continuous buzzing sound occurs, which wont stop till i switch it off.


I'm posting this from the same laptop,which seems to be OK now, but would hang up in a few minutes from now.

Please help!
Fix me !