Shoutbox

Recently, I've noticed that my computer keeps becoming unresponsive.
What happens is that say I insert a USB drive or try to start a game, and the computer becomes almost totally unresponsive.

I am still able to move the mouse (usually) but I cant click on anything.

I have no idea why this is happening, and I havent really made any changes to the system lately (Latest change to the system would have been installing drivers for my new webcam, but that was working fine when I originally installed it)

I have noticed that HDD light doesnt come on like it used to (or at least i dont think it does). For example when Id start a game or something, youd see a constant flicker of the HDD light, but now when I do it, its on for like a second then off for like 5-10.

Any suggestions as to what it might be/how to fix it?
Im borderline about to reformat to see if it makes a change, but because uni has just started, id really rather refrain from doing that.

Thanks