Computer Crashes

[saila]

Well Im New Here and my computers getting on my nerves lol.
My Computer Keeps Crashing . Makes 3 funny sounds and switches off . If I Go On Msn It works Nomrally But when i have too many things going at once it switches off for example when im on youtube it just switches off whats wrong with it :S

 

[Tmagic650]

The hard drive may be corrupt and you may have a failing power supply