The browser you use won't change your IP address. If you're using a public wireless access connection, or a mobile connection, or something similar (school network, etc.) where either IP addresses are rotated frequently or a lot of users are using the same public IP address through a local network address translator, you could be suffering for somebody else's misdeeds. You can use the tool at
http://whatismyipaddress.com/blacklist-check to see if the public IP address you are using has been added to spam/bot blacklists, which are shared by a large number of service providers and websites. If you see your address added to a large number of lists, you may have to take it up with your internet service provider, or try accessing the internet from another location.