Darkflame

Hello.

I'm really new here, and more so to overclocking; I recently got Left 4 Dead, and, being as old as my computer is, it didn't play as well as I had hoped. At first, I searched for ways around it -- using direct x level 7, for example. However, after a while I decided to use overclocking - a technique I know little about. Here's the problem:

I just overclocked my computer, and after doing so, my sound appears to of gone odd. I have 5.1 surround sound (Logitech), but after overclocking only two of them are playing sound, and the two that are are extremely quiet. Before, I could spin the sound wheel to half before it was unbearably loud... now I can get to full and it's at a decent level! The quality is no different, so I'm unsure what I've done. I'd just like to state, them I'm only fourteen, and as such, many of the abbreviations and terms you use I may not recognize, plus this is a reason why I believe the overclocking caused it.
These are my specs, plus what I did:
Dell Dimension 5150
Intel Pentium 4 CPU 3.00 GHz
1.5 GB RAM
ATI Radeon X600

I know that I have these, but, oddly, looking at a program called Ccleaner, a temp file deleter etc, it says I have 'ATI Radeon X300/X550/X1050 Series'. Glitch?

Anyway, using ATITool 0.26 and a guide I found, I started to overclock. At default, 'Core' and 'Mem' (CPU + Memory/RAM?) were at 400 MHz and 250 Mhz, respectfully. After overclocking, it was raised to 505MHz Core, and 310 MHz Mem. Now, after a restart, game performance is better, for certain, and is still remaining cool, however, the sound has been reduced, phenomenally.
A couple of things I'd like to point out:
I did use Ray Adam's Tray Tool's, I fiddled with a couple of settings but I didn't understand it, so I uninstalled it.
I decided to use a system restore to repair the sound, but this was to no avail.
I'd also like to mention that I've searched through all the of the Control Panel options I know, and, this may confuse you, it is set on Headphones. This is not an accident and is because the sound was used for both my PC and my Xbox 360, so, it would be plugged in normally for PC, and a wire connecting the sound for the 360 and that for the PC would be connected in to the headphones, this allowed sound on both the 360 and PC at the same time. Though, I don't think that'd change anything.

My worry is that it's permanent damage, but, seeing as the quality is still good - even though its quiet - I doubt this is it -- fingers crossed! My question, after all that ranting is: have I overclocked right, if not, how do I do it right, and, most importantly, how do I get sound back?
Thanks guys, if you need more information, please tell me what you need, and how I can get it for you. Thanks once again