Kubuntu 18.04 and HDMI

[Jim]

I have a box running kubuntu 18.04 64 bit and an NVIDIA Geforcee GT520 
video card.  The first monitor is connected via the DVI connector.  The 
second monitor using the HDMI connector. I also use the  second monitor 
for the cable box and I have an hdmi switch to connect the second 
monitor to the computer or the cable box.

The problem is that the computer doesn't recognize there's an hdmi 
monitor connected.  Sometimes it does this when I boot up the machine.  
Sometimes when I have the second monitor connected to the cable box and 
switch back to the computer, I don't get the second display.  If I'm 
lucky, restarting the x server will work. Sometimes I have to reboot the 
machine.  If it really wants to be a pain in the ass, I have to 
uninstall the NVIDIA drivers, and restart the x server.  Then the 
Nouveau drivers are used and it works.  That is, until the next time it 
happens and reinstalling the NVIDIA drivers fixes the problem.  Until 
next time.

When it's not working xrandr says HDMI-1 is disconnected, even though it 
is connected.   Is there something I can do to  restore the second 
display without the rigamarole of uninstalling/installing drivers?  I 
tried using the second monitor's VGA input.  That works, but I then have 
to use the sound card in the computer.  Because of the cable box, 
there's an annoying hum in the audio.  I can deal with that by 
connecting a wire from the case of the computer to an alligator clip 
which I connect to the coax input to the cable box.  Then the clip comes 
off or I bump something and that annoying hum is back.


Any ideas?  Thanks