If this is what I think it is, then this isn't a computer tech issue. This is a known Warcraft 3 bug.
The problem comes from, if I recall correctly, the Dungeon sound environment alongside certain sound settings. Switching to "Miles Emulated 3D" Fixes the bug for the player (Again, if I recall correctly), but the bug can also be fixed in the map by not using the offending sound environment. (Set in Scenario Properties in the editor, yet again, if I recall correctly.)