Computer. I have a free version of AVG antivirus intalled in my computer at home. As you know it

Question

I have a free version of AVG antivirus intalled in my computer at home. As you know it doesn't provide protection against spywares. So if i install an anti spyware will it cause any problem as there is an anti virus already present. Also these days my computer hanks every now and then.Recently i formatted my computer. Also when i start the computer sometimes an error message comes saying log in error with that send and don't send option. Can you tell me the reason.