Please help. Mac book pro only connecting to certain web pages

Mac book pro version 10.6.8

It started last week, only loading certain web sites

I bring my computer to school and it connects fine. I also brought it to my parents with no problem.

My iPhone connects to wi-fi just fine and I've talked to my ISP, they say the connection is fine.

It's driving me crazy!

It goes to some web pages but won't load for others. The little blue bar across the top will just stop

I've tried talking to my ISP

I deleted all cookies and emptied the cache

I'm not sure where to go from here