hard disc problem, please help!! I need a program that could help me understand what is the problem!!

It's a western digital 160gig, It worked great for 6 months and now I got some big problem, but I don't know if it's the hard disc...

my pc is crashing often when I download on my D:/ ( the western digital 60g ). When I open a file, sometimes I freeze my computer... :S, ( everytime for the same file, ISOs mostly ), so I tryed to use the disc check of windows, but it crashed :|, I tryed to defragment my disc, also crashed... Can you suggest me a good program? I'm not a computer n00b, I'm sudying in network at montreal. But as you can see, I'm studying, I'm not done with it, only 1 year of study. So please help me.

I need to know if it's windows who's constently crashing OR my hard disc ( I suppose it's my hd, but I need to be sure ). So if you have a good program, tell me plz!