A lot of internet pages won't open because i changed my internet connection to another company. cont...?

soo everytime i take my laptop to a friends house or a placer with a different internet connection than the one at my house a lot of pages won't load. pretty simple pages like justjared.com/ tvshack.cc/ sometimes even facebook or isohunt.com so today i changed my company because we didn't like the old one and im having the same problem with these pages. what can i do to fix this?