|Malware may be shutting off your firewall. You may want to do some malware checks with different free software, like malwarebytes, etc.|
Sorry, unless you have a laptop, why may I ask that you use the sleep mode? It was designed to preserve battery power on a laptop.
On a PC it is all preference. I run mine with everything set to never and have never had any problems. My PC stays on 24hrs- screensaver working plus I blow out the chassis every 6 months to remove unwanted dirt off the fans to keep it running cool (I reboot at least once a day to clear the cache) and only gets turned off if I go away for a weekend or if there is a bad lightning storm.
Some HELP in posting on Computing.net plus free progs and instructions Cheers