[Skullmeat]

I also noticed that when PC freezes the HDD light stops blinking even when PC was Installing large software which would require big HDD usage and I read somewhere that it also could be the HDD dismount problem where HDD dismounts for short period of time and mounts back again and that makes PC freeze. Could that be a possible problem?

It could be, but until you test a different HDD can't know for sure it's an HDD issue in the first place.

Replaced with the HDD that I've found and seems that my HDD is really dying because the one I put in now seems to be running well no freezes nothing just a bit slower since it is quite old but I think it will do for some time till I get new Hard Drive. Quite disappointing that 1TB drive died faster than 320GB old one which I have for around 5 years now.

Also a question, I got lots of Laptop HDDs is it okay to mount them in to PC and use it as normal HDD? Just a question I was curious about.

You can. Laptop drives use SATA as well. However, make sure you have the proper mounts for the smaller form factor, as excessive vibration is bad for mechanical drives.