Computer speakers help

I have Altec Lansing speakers (surround sound with a sub woofer). Couple months ago, the speakers decided to play really quiet, so I plugged the headphones in and used those for awhile. Now I’m actually determined to figure out what the problem is.

Right now, my sound is halfway turned up (on the speaker, not in the sound controls) and it’s very quiet. But once and awhile, my speakers will, say, correct themselves and play to the correct volume as they should, but it’s for a split second. All my wires are in great shape, no cuts, not pinched, nothing in that matter.

Any ideas? I’ve tried looking up drivers but my buddy said it sounds like more of a hardware problem than a software problem.

If it’s any help, I have a pair of these (http://www.modsynergy.com/Modsynergy%20files/Altec-Lansing-2100-connect-.jpg) in the back of my computer, and when I do jiggle the wires, the sound is affected and often gets VERY quiet. Any ideas would be great, thanks guys.