I'm having the same problem and that beep is driving me crazy. The above mentioned solution from the macrumors forum works more or less. In the vm in settings -> ease of access -> Mouse -> mouse keys. I have to switch the option "use numeric keypad to move mouse around the screen" off. However after a reboot of the virtual machine this option is switched on again. If you are using a headset as I am usually doing you nearly get hearing damage because of this beep. This is really annoying.
It seems a bit strange to me that either windows 10 or Parallels keeps switching options on its own. Does anybody have any ideas on how to fix this before I turn deaf? Oh yeah. I did find out, this also happens if I connect a usb of bluetooth device to my mac. It doesn't matter if I use this device in the vm or not. If the vm is running the above option automatically switches to "on". It seems like a bug to me, but what do I know?
Last edited: Apr 20, 2016