IE or Firefox won't load all bookmarked pages

I can't get about half of my bookmarked pages to load today. All of them loaded yesterday, but today about half of them won't load. I tried using IE and Firefox. I use Firefox 95% of the time, and that's where I have the pages bookmarked. None of them are bookmarked in IE but they won't open in that browser either. I try typing the addresses into the address bar manually and they still won't load. Anyone have any idea what could be going on?

One other funny thing is that I can get to the Yahoo! front page, but can't get Yahoo! mail to load.

I use Verizon DSL and a wireless router. I connected direct without the router and had the same issue. Could Verizon be having issues getting to certain IP addresses?

My neighbor uses the cable company to get to the internet and he can load all of the pages without any issue.

Any help or advice would be appreciated.