wired computer laggy

[hs19851224]

hello guys,
i'm new register here.
i have a really wired computer laggy phenomenon. i was used to download moview/songs/software using utorrent (a torrent download software). it was fine for the past half year. how ever, recently wired thing happen. when i play WOW/SC2 or watch movies while i downloading something. my computer will freeze for like 2,3 second. meantime, i feel the CPU stop running because move paused (i didn't pause the movie, it automatically pause for 2,3 second), song crash( then sometime it will skip the current song, continue play for next song). after all those thing happen, i was wonder if my video card or CPU is over temperature. sadly they are really low temperature.
when i don't download, everything works fine. then i start thinking maybe the hard drive problem. i check the hard disk using the windows command: CHKDK. it didn't find any
error or broken sectors or volumes.

so my question is: how can utorrent make this happen?

i appreciate for any help.
thank in advanced!

[hs19851224]

btw, i forgot to mention that i install my OS on C drive which is a 120GB SSD, so is utorrent.
but the director where utorrent download file to is in D drive which is another HDD that separate from SSD.

[QuantumPhysics]

Okay, your translator is a bit off.

But here is a quick fix to prevent your computer from being so laggy:

http://forum.utorrent.com/viewtopic.php?id=74820

Utorrent is a memory hog.

Remember to reboot your computer after!