I, too, have custom-mixed my sounds over the years.
Also, a lot of these sound problems are related to the sound card hardware itself, I'd guess.
If the on-board sound chip your squaddie is running has a hardware fault at some point in that sound file, it could trigger his disconnection, but your sound plays over your Sound Blaster Audigy (?) without problems.
See what I mean?
I've had a couple of bad sound files, and a couple of bad gunsights, over the years. Mostly the sounds just suck, I've been lucky with crashes and all that.