That's the BIOS. It finds the CMOS settings wrong, so asks you to correct them. The BIOS is a part of your PC you don't see if everything is fine, but that is necessary nonetheless.
I'd start with pressing F2 and see what happens. And it might be time to replace your motherboard battery.
That antivirus problem is unrelated, most likely, both to the WiFi printer and to the BIOS. But you only know for sure if you fix that BIOS message first and then (if necessary) uninstall that printer.
About last 2 days, e.g. Rightnow, when I switch on computer in morning instead of usual Windows starting screen I get a provisional-looking screen American Megatrends starting 'initializing USB controllers...done ... Various stuff... CMOS Setting Wrong
Press F1 to Run SETUP
Press F2 to load default values and continue
I started to do this then thought who invited you? I have never heard of you, and I aborted this.
I got into my normal system somehow. I get warnings from my free AVG firewall/antivirus that I am at risk, I have to fix the antivirus which is done pressing a button 'fix', ignoring offers to buy enhanced protection. Next day same thing happens, antivirus has to be reactivated.
What had I been doing out of ordinary recently that might have provoked this? Well I had installed a new printer all wifi which works. My impression - this is something to do with wifi.
What is going on and how do I get back to normal?