Hmm, I'm not sure how I can help here. I'm no PC sound card specialist. If you, as you say, have this problem with all your sounds and all your PCs, I hope that it's not a matter for an ear specialist wink.

Reinstalling 3DGS does not help with such issues. The first thing is checking what all your sounds might have in common - maybe you've created stereo sounds with volume on one channel only. Next, look for possible PC problems. Maybe you have the same driver or background program installed on your PCs that tampers with sound playing. Finally, check if your speakers are properly plugged in. That's all possibilities I can think of.