I checked from another machine on my network, and it looks fine as its loading all the websites. This is strange!
Would that machine be your firewall by any chance? If so, you may have MMS clamping issues. One possible cause is manaully restarting your firewall, which bypasses the /etc/ppp/ip-up.d/0clampmss script run by pon/ifup to configure the MMS clamping parameter. Another possible cause is your pppd MTU setting.