BleepingComputer.com: AT&T Yahoo! Browser

Hello. Can anyone help me. I currently have AT&T Yahoo! Browser installed and use it to access the internet. I also have Internet Explorer installed but I cannot access the internet from Internet Explorer. I get the error message "Internet Explorer cannot display the webpage." Also, if I install AVG (anti-virus) free version I cannot access the internet with AT&T Yahoo! Browser. I have to uninstall AVG and then I can access the internet but only with AT&T Yahoo! Browser. I would like to uninstall AT&T Yahoo! Browser but I am afraid that if I do I won't be able to access the internet with Internet Explorer. I would like to just be able to use Internet Explorer and install AVG because I currently don't have an anti-virus program running. Thanks.