A friend is having a problem with mIRC 7.32 (under Windows 8) beeping upon any private message—even with the window focused. He's tried turning every sound related thing, and flashing off, and even a totally from scratch install.
I think what he was looking for is in the options ALT + O > sounds > beep on message > [x] query. Ripping out every trace of mIRC and reinstalling solved the problem because there is no beep on query by default
#mircscripting @ irc.swiftirc.net == the best mIRC help channel
That was cleared; he even set beeping to off in the window-control menu.
(I've had a past (about 15 years ago 😮) version of mIRC get something strange (i forget what) stuck in its craw, like this. Resolved it by whacking out the options section (the one that's just a sea of numbers) from mIRC.ini.)