I have an ASUS P4T533-C based system with a Pentium IV 2.26Ghz chip, 512MB of RAM, a Leadtek GeForce 4 Ti 4400 graphics card, all running under Windows XP Pro. I am using the motherboard onboard sound - two Advent desk-top speakers plugged directly into the Line-Out jack on the board. Two days ago, for no apparent reason, the left speaker quit working. I checked all the cables, and all the volume control levels and everything appears to be as it should. I plugged my speakers into another system and they both work fine. I plugged another set of speakers into my system and the left one didn't work. I plugged a set of headphones into my system and the left channel doesn't work. I have tried uninstalling/reinstalling the drivers for the onboard sound, and it has no effect. When checking the cables I noticed that when I pulled the connector slowly out of the jack until it was almost completely out the left-hand speaker suddenly began working again. Pushing the plug back into the jack made the left-hand speaker stop working again. I've pushed and pulled and changed and checked and uninstalled and installed and reinstalled and rechecked and am now completely frustrated. Any suggestions welcome.