Can't access Google & CNN

I've got a really odd scenario ... for some weird reason, I haven't been able to get to CNN, Google or successfully use my Google toolbar search option for a couple of days. I doubt their sites are down, but I haven't (knowingly) done anything to my internet settings to prevent me from getting to them ... IE just sits there waiting for the site to reply ... eventually times out or tells me the address is invalid. I even retried searches that worked last week from my internet history.

All other sites I'e tried work ok. It's so strange to be limited to certain sites ...

Any ideas? I'm using Norton's Internet Security package, but have not adjusted the settings since installation many months ago.