Deezmon
I agree with you.. /beep should work on a system with no sound files no sound card no sound drivers no codecs and no external speakers if the system has one of those little speakers connected to the motherboard as most desktops do.. the sound is actually on the motherboard in hardware probably just a simple astable multivibrator circuit same one used when the motherboard beeps out error codes.. in other words the /beep is just a signal to that circuit not some sound file built into mirc.exe.. yours not working could be a hardware issue.. have you been inside your box lately and maybe disconnected the little speaker from it's motherboard header?
