Firstly what version of Comodos firewall do you have?
What other security aplications were active when you downloaded cpf?
Dose the f/w only block google? and what do you see on your screen when it blocks and attempt to connect to google?
What browser are you using?
Allowing all in your firewall is not advisable, as you have no inbound protection.
Maybe a clean install will sort this problem, have you tried uninstalling and reinstalling in safe mode?