Thank you buddy !!!
I migrated from VMware to parallel and this beep noise was annoying me a lot and this fixed that...
I just toggled off ((Turn on mouse keys))
5 years later, I ran into exactly this annoying beep; every time I switched to (and from) Windows (11) in Parallels back to Mac OS (Sonoma) I got an annoying old-school 'motherboard' beep.
And THIS fixed it! I don't know what turned it on, and why it gave the beep switching windows, but I'm a happy camper.
START > EASE OF ACCESS > MOUSE> top switch for: CONTROL MOUSE WITH KEYPAD