No sound

[ttodd72]

I have a Dell e521, AMD Sempron Processor 3400+, 1.80 Ghz, 3.00gb ram, Dell motherboard, my onboard sound card has recently gone undetected by windows that, driver was sigmatel Stac 93XX, I tried reinstalling the driver but keep getting the message that my system does not detect hardware, so i installed an Explosion HDA 7.1 sound card, but I still have no sound, the weird part is when i PLAY wow, I can here the game and use my mike, same thing on vent, so why can i not here regular sound from either watching videos via internet, music from frostwire or anything else that has nothing to do with vent or wow?, I am downloading Realtek AC97 to give that a try

 

[Tmagic650]

Your system may have a virus or malware infection. What protection are you using?

 

[ttodd72]

I upgraded from norton to AVG PRo, turned out norton was part of an earlier problem, AVG seemed to have fixed everything, Sound problems started happing later on, I installed a graphics card GE Force 9800 512 and thought that may have been a problem but when i reversed everything nothing changed.