Hard drive

Well, I've been having a lot of problems lately with watching movies and such.
The problem is , that every 1-5 minutes or so (sometimes even 20 or more) the picture freezes for 5 sec - 5 minutes .. I've tried everything and nothing has worked, tried different players but still no luck... So I was wondering if anyone would have any idea..

Are these retail movies or ripped movies?

Well it doesn't really matter...

Now the problem has evolved, when playing games like GTA I have "lag spikes" like every two minute or so.. I tried to solve it with another windows on my pc (64 bit on a seperate disc) but the same deal there, lag spikes , screen freeezes every minute or so...