Re: computer lags w/ associated USB device disconnect sound
It sounds like it could be an issue with corrupt drivers, faulty hardware or a loose connection for something like a media card reader, sound card, touchpad, keyboard, etc. If you know how to take it apart you could do that and make sure all of the ribbon cable connections are secure.
Also, When something gets connected/disconnected it will usually show in device manager. So, you could look there to see if anything shows up with a yellow "?" or "!". Try updating some of the drivers for the above mentioned hardware as well to try and resolve any corrupt driver issues.
Another thing to try would be disabling some of the devices in device manager like the touchpad (since you said you use a wireless mouse), and see if the problem persists. Although, you should be careful if you aren't familiar with it as you don't want to disable something that could cause you more problems.
Hope this helps and good luck.