Best thing to do is to find out if it's a Sound Card related problem mate. Try these things to see if you can narrow the problem down to what it is.
What's your operating system Paul?
If it's XP, go to the Start up menu and click on Control Panel. Then click on Sounds, Speech and Audio Devices. Then click on Sounds and Audio Devices.
A little window should pop up with some tabs on the top of it. Click the last tab which says 'Hardware'.
You should see a list come up of everything that's to do with your sound on the computer - cd drive etc... The first thing in the list should be highlighted and you'll see a little description at the bottom of the little window that opened up, saying if the device is working properly or not.
Just click once on each thing in the list to highlight it and see if the description on the bottom, says if anything isn't working properly.
If everything is ok in that list, then the best thing to do is to go to your Device Manager. Close the windows down you've just opened.
Click Start, then right-click on My Computer. Select Properties, then select the Hardware tab. Then click on the Device manager button. This will bring up a list of all things in your computer.
Move down to where it says 'Sound, Video and Game Controllers' and click the '+' sign next to it. Another sub list will appear.
If you see any yellow exclamation marks next to anything in the list, that's where your problem is, so make a note of it. As to what you do if you find a problem, I can't help you there. It might be worth googling the problem (if you find one of course). Because no doubt someone else somewhere will have encountered a similar problem to you.
If you don't find anything wrong, it might be worth having a look at this forum I've linked and possibly even posting your problem up. Good luck mate.
http://forums.techguy.org/
