honestly i am not network expert especially on new mobo (i know old)...
if i am you.. then i would start to check hardware problem... or check driver for latest update from asus p5q-e (???) -- if fine then try to clean unistall and re-install... use this
Revo Uninstaller Freeware - Uninstall, Remove Programs, Solve uninstall problems ( check other if you want)
then check your modem config especially wireless setup if you use wireless ( i am still not sure if you use wireless or ethernet wire)
wireless config in 2wire is really unstable... make to sure you use CORRECT ip number and name... [it tooks me two day to find a right ip/name to work on four computers plus tv....]
ps. try default browser such as IE7... or maybe do you have software firewall (disable it temporary) before go ahead that above?