Sound sometimes works.

Hi,
So I've been having this problem ever since I installed Windows 7. My Sound magically stopped working when upgrading from xp home. I looked at the cord from my speakers to my computer and noticed the male pin going into the computer was sort of bent so I bought a new one.I realized forgot to install my chipset drivers and sound drivers so when I remembered I installed them, restarted, still nothing. I then decided yesterday to install a fresh copy of xp pro that I had gotten through my college. I knew that my sound had worked when I had xp running on the machine prior to installing windows 7. After the installation of xp pro, chipset driver and sound drivers the sound still did not work. I was angry about it but decided to play Counter-Strike source. My volume was up fairly high, the next thing I heard was a ton of crackling then a bunch of sound from the game. I thought this is weird but whatever my sound works for now. I played a game and the maps changed and my sound disappeared but once again had some crackling then came back. I thought maybe it was working for good finally. So I decided to play some everquest. Well the sound did not work in everquest. Now i am so confused on why it would work in Counter-Strike but not another game, or any other application/website that has sound to it. Does anyone know a solution to this? Or any reason why something like this is happening? thanks in advanced.