My HDD is “ticking” and freezing my pc

Hi,
I am running Windows XP SP3 in regular load, and my HDD is a Samsung (I don't know about the exact model, i can check if needed). My problem is that, i boot my pc, start working on normal tasks (say surfing the web), and after some minutes my HDD start doing a noise similar to a "Tick", like if it were skipping over data constantly.
It does it a few seconds and then it continues. In the meantime, the PC freezes completely, and then also continues normally. I'm wondering if it may be related to some bad cooling, which i don't really think as i am in a cold region and its winter now, or a disc failure, and how would i go to diagnose it? I need some urgent advice as in case its a bad issue i should backup everything right away.
Thanks.
