Computer completely freezes

hi,
Im running Windows 7 32bit, all latest updates and drivers. specs. q6600 @ 3ghz, 4gb ram, asus radeon 4870 (all working fine)
2 BRAND new hard drives, as in in the last month (2 x 500GB Seagate Barracuda 7200.12)
basically, it just freezes, everything freezes (but the keyboard doesnt) it just locks up on me, I’m virus free too.
I cant seem to see what the problem is. Its not when Im encoding or anything or playing games, Im just browsing the web listening to some tunes, watching youtube videos then everything stops responding, I can ctrl + alt + del, everything crashes, yet I can still use my mouse.
any help thanks
Answer #1
put
eventvwr.msc
into the search box and check your error log for clues
will it boot and run in safe mode ?
Answer #2
yes, the pc runs amazingly well, playing all latest games really well, its just sometimes – everything freezes. its not doing a certain task, it just freezes, cant ctrl + alt del or anything, but I can still clicking icons and stuff (but they dont open)