[H] HP Compact DC7800 continuous beeping

[Steve Tomporowski]

Got a weird problem.  I acquired an HP DC7800p ultra-slim tower (well, 
they were throwing it out).  It set up fine in Linux Mint, so I lent it 
to our in-house contractor.  He plugged in his cordless Microsoft dongle 
and everything was fine until the next day at startup where the system 
refused to boot and beeped continuously. If he plugs in the dongle after 
boot, then all is fine, it just won't boot with the dongle in any USB 
port.  According to HP the continuous beeping is a 'Serious system issue 
such as CPU overheating'.  Well, sorry HP, wrong again.  If a corded 
mouse & keyboard is plugged in, there is no problem, only with this M$ 
dongle.

Anyone encounter this weirdness before?
Thanks...Steve