Technical issues with Heroes III.

Something completely inexplicable is happening to me. When I try to start a game through the online lobby, I hear snippets of system sounds, followed by beeping noises, as if it's Morse code, and the online lobby freezes for the second player, whoever they may be. If I try to connect to someone, the lobby freezes for me, even though the second player doesn't hear any sounds. Reinstalling Heroes of Might and Magic didn't help, nor did trying a completely different build. A complete reinstall of the online lobby also doesn't help. The antivirus software didn't find any viruses.